Nights In Lankhmar
The base coin of the realm is the Bronze. A bronze will buy you a decent ale, a well-made candle, or a very basic cap. Almost everything is priced in terms of the Bronze.
The main coin of the realm, however, is the Copper, which is worth 5 Bronzes. Most well-to-do people carry Copper coins, with Bronzes acting as change. (This is similar to how the $20 bill is the de facto bill for most U.S. transactions even though prices are set in dollars and cents.)
Below the Bronze is the Tin – a purer metal, true, but also a nickel-sized coin compared to the Bronze’s half-dollar size and less precious than the alloy. There are 10 tin coins to a Bronze, making a Tin roughly equivalent to a dime.
Above the Copper is the Silver, which is worth 10 Coppers. Above that… most people quit trying, but in Lankhmar some high class venues will accept Gold coins (worth 10 silver).
10 tin = 1 Bronze
5 Bronze = 1 Copper
10 Copper = 1 Silver
10 Silver = 1 Gold
1 Gold = 10 Silver = 100 Copper = 500 Bronze = 5000 tin
After than you have to contend with gems, appraisal, and haggling. Most people just use writs of credit at this juncture. On the one hand gems are very valuable, measured in increments of Silver. On the other hand a gem is a gem is a gem, with few caring if the stone is diamond, amethyst or emerald. They are ultimately worth whatever the buyer is willing to part with.
In game terms a bronze is equivalent(ish) to a pair of copper pieces in the D6 system (2 CP), but it’s not always the case. Finding a price list that’s both comprehensive and sensible is very tricky, and then trying to map that back to the D6 system’s limited price list is maddening. I will try and get a standard list of “normal” costs for things — understanding that haggling is commonplace and prices vary wildly based on location and demand.