With one price a dealer chooses between customers who would pay more and customers who only buy for less. Selling to groups of customers at different prices is what economists call third-degree price discrimination; nearly all firms with market power use some form of it [1].

The Perth Mint strikes at most 500,000 of the 2026 1 oz Kookaburra [2]. It sells from about 11.6 % over spot at the cheapest of nine dealers compared [3]; one dealer asks 4 % more when paid by card than by bank transfer [4]. So dealers buy it below 11.6 % over spot, and earn a few percent on it.

A collector of animal-motif series such as the Kookaburra buys the 2026 coin to complete the series, not for the ounce, and compares less on price. What collectors pay shows in the series: the same 1 oz Kookaburra of 2018 is offered at $106.44 [5], the 2026 coin from about 11.6 % over spot [3]. Special editions of the 2026 1 oz coin are limited to 2,500 and 3,000 pieces [6, 7].

Prices are lower where a competitor is close: the Australian competition authority found supermarkets with a rival within one kilometre 1.36 % cheaper [8]. Retail chains set prices by the competition in each local market [9]. A store with no other dealer nearby can ask more.

Large buyers compare quotes and switch dealers; a quantity discount wins orders that would otherwise go elsewhere [10]. One dealer sells the 1 oz Kookaburra 1.9 % cheaper per coin from 20 coins and 2.8 % cheaper from 300 [4]. The profit per coin falls, the total profit rises with the volume.

People buy differently at different times. A study of in-store purchases and online food delivery found price sensitivity falling by about 0.5 % per hour over the day: morning buyers hunt for deals, evening buyers switch less [11]. Shoppers judge the same online promotion differently in the morning and in the evening [12], and online retailers already change their prices at different times of day [13]. The investor at 10:00 on a weekday compares every offer; the buyer browsing on Sunday evening compares less.

The cost is the coin's silver value at today's spot plus a supplier premium. With one price every customer pays on cost, about 11.8 % over spot as in the market. Collectors pay 8 %, the small-town store 1.4 points more than the base, the business customer 1 %, Sunday evening 1 point more. The coins customers buy change with an assumed price sensitivity, low for collectors, very high for business customers who compare quotes. Illustrative figures.

A bar earns its profit on the day it sells. Every day before, it costs: the money tied up in it, the vault it lies in, and the profit that money could earn elsewhere. Each cost is a rate per year; the table charges it for the days the bar is in stock, cost × rate × days ÷ 365.

Dealers finance their stock through their liquidity provider, often with metal: on consignment or as a lease, the dealer holds the provider's metal and pays a fee on its value. Providers such as StoneX offer consignment accounts and metal leases [1] but publish no rates. Such fees are a market rate for lending metal plus the provider's markup [2]. Gold lent to jewellery manufacturers and refiners earned its lenders a year in June 2026 [3]. With a markup of points, an assumption, the default is a year. A dealer who pays with its own money pays no fee, but the money then has an opportunity cost.

Professional vaults charge a share of the metal's value per year. BullionVault charges a year on gold, insurance included [4]; Goldmoney charges 0.25 % a year at all its vaults [5].

Money in a bar that does not sell cannot buy products that do. A-Mark, one of the largest precious metals traders in the US, earned a gross profit of of its revenue in the year to June 2025 and turned its stock times [6]; turnover is cost of sales divided by average stock [7]. So every dollar of stock earned about in gross profit that year: ÷ (100 % − ) × .

The financing fee is paid on every bar in stock, also on bars that sell fast. If the money would otherwise go into faster products, the slow bar costs above all the profit forgone; set the financing to zero to count only that.

The bar costs the gold value of 20 g at today's spot plus and sells at spot plus , within the 2.0 to 2.3 % over spot that dealers ask for this bar [8]. The purchase premium is illustrative.

Gold and silver trade mostly over the counter in London, directly between two parties and not on an exchange [1]. What was traded at which price is not published [2]. The only fixed reference is the LBMA Gold Price, set in an auction twice a day, at 10:30 and 15:00 London time [3]. Between those auctions, "spot" is whatever a data provider shows.

Bullion banks quote prices to buy and to sell, and each data provider combines the quotes of its own set of banks into one figure [2]. So two providers differ:

• Other banks. Each provider takes the quotes of different banks.
• Another moment. Providers update at different speeds; in fast markets the screens of banks can lag behind [2].
• Bid, ask or mid. One shows the price to sell, another the price to buy or the middle of both [4].
• Spot or futures. Some prices come from the futures market, not from spot trading [4].

If the supplier invoices in another currency than the one in which a spot price is quoted, the exchange rate comes from a source and a moment of its own as well. Even the European Central Bank's reference rates are set once a day and, as the ECB says, are not meant for transactions [5]. Equal spot prices in dollars can still give different prices in euros.

The supplier invoices on the spot of its provider, at the moment it books the order. A dealer who calculates costs on another provider's spot, or on an older tick of the same one, has costs in the system that are not the invoice. The gap is small, often 0.1 to 0.3 %, but it lands on every ounce, and when the calculation is too low the dealer sells below the planned profit. The Margin Optimization Platform calculates on the same spot, from the same source and at the same moment as the supplier, so the calculated cost is the invoice.

Many systems convert at a reference rate that is set once a day. Such rates exist for every major currency pair. The WM/Reuters closing spot rates, fixed at 4 pm London time, are the market's common benchmark for valuations [1]. Central banks publish rates of their own: the European Central Bank for the euro, set around 14:10 and published around 16:00 CET [2], and the Bank of England for sterling [3]. Each shows the market at one moment of the day. The ECB publishes its rates for information only and discourages their use for transactions [2]; the Bank of England calls its rates no more authoritative than any commercial bank's [3]. The example uses the euro; the same holds for any two currencies.

EUR/USD moves by about 0.5 % from its low to its high on an average day in 2026, more in busy weeks [4]. A price converted yesterday at 16:00 is still on yesterday's rate the next afternoon.

The profit on a gold coin is a few tenths of a percent of its value. A move of the dollar by the same few tenths takes all of it: the supplier invoices in dollars, so the cost in euros rises with every cent the dollar gains.

The supplier invoices the coin at today's gold spot plus . The shop price is that cost in euros at yesterday's rate plus of spot, as in the chart above. The dollar's path through the day is illustrative, a little above an average day. All prices from today's gold spot and euro rate on this site.

Every price starts from today's silver spot, the same source as all prices on this site. A 1 kg bar holds troy ounces, so its spot value is . The three other shops ask spot plus ; dealers ask from about 3 % over spot for a 1 kg bar, on average about 7 % [7]. What the shops pay their suppliers is not known. The dealer's own purchase cost is the black point on the range, by default a bar at today's spot, that is spot plus , an example. The price starts between shop A and B. For comparison: A-Mark, one of the largest precious metals traders, reports a gross profit of 1.9 % of revenue across its whole business for 2025 [1]. With a good purchase cost the dealer can be the cheapest and still earn. With a higher one, the cheapest place sells at a loss and the best price sits higher, with fewer bars: nobody can always be the cheapest. At the default purchase cost the best price is , . The price can be set from spot plus to spot plus .

Buyers compare the four shops as on a price comparison site. Each buyer picks one shop or does not buy this month, following a multinomial logit, the standard model of choice between offers [2]. buyers a month look at this bar. Three effects measured on price comparison sites for identical products set how they choose:

• Price. Every percent above the cheapest offer costs demand. Ellison and Ellison found demand for identical computer parts on a price search site extremely price-sensitive [3]; an early version of their study estimates an elasticity of about −50 [4]. The model uses .
• The cheapest offer. A shop gets about 60 % more clicks when it has the lowest price on the site [5]. The model adds .
• Place in the list. The further down the list, the fewer clicks, with the log of clicks falling in a straight line with the rank [6]. The model takes off for each place.

Profit a month is the bars sold times the price less the purchase cost; below the purchase cost every bar sold is a loss. The model tries every price in the range, cent by cent, and keeps the one with the highest profit: the best price. Missed out is the profit at the best price less the profit at the price set. Being cheaper than needed costs profit on every bar; being more expensive costs bars.

The figures are illustrative. The studies looked at computer parts and electronics; we found none that measures sales and prices for precious metals. A 1 kg bar is just as identical from shop to shop, but trust, delivery and stock also count, which is why the most expensive shop still sells a little. With a dealer's own sales and price data the model can be fitted to its market.

The 50 yuan Panda of 1990 was struck for the Hong Kong Expo: a gold centre of ½ oz in a silver ring of ⅕ oz, as a proof, 2,000 pieces [1]. At today's spot the metal is worth .

Collectors pay for the issue, the mintage and the condition, not for the metal. One dealer lists the coin at $4,495 [2]; a piece graded proof 69 sold at auction in May 2024 for $1,920 [3]. The price of the same coin can double or halve with demand, while spot moves by a few percent.

Metal value plus a fixed premium follows spot and nothing else. When the coin is sought after, the shop sells below what collectors pay and its stock goes too cheaply; when interest fades, the price stays above the market and nothing sells. Buy-back works the other way round: at a fixed price nobody sells to the shop when collectors get more elsewhere, and the shop pays too much when interest fades.

The coin sells for about twice its metal value, so the system sells at metal value + and buys back at + . The three situations, collectors paying + over metal value, are illustrative, as is the collectors get less when they sell elsewhere. A difference of up to 1 % of the metal value counts as at market. Gold and silver from today's spot on this site.