generally speaking the most complex is the orcs:
1. you have copper, silver, gold, bonemold, and platinum coins.
2. very few things that can be bought from the vendors can be sold back to the vendors.
3. what can be sold back is almost always sold at 1/2 what the buy value is.
4. each purchase and sell has its own reaction, the fact they are linked to skills(negotiation generally) cause the coins to have "quality" levels, making some coins of the same type extremely valuable for depot trades.
5. the value is set in stone and unidirectional, you can't break down from say bonemold to copper. end products are bonemold and platinum
2500 c->1,000 b
500 s->1,000 b
500 g->3,000 b
5,000 c->1,000 s
5,000 s->2,000 g *which directly would of been 10,000 b but through this makes 12,000 b
5,000 g->2,000 p
6. there are 3 fake coins that can be converted into bonemold coins... zinc, lead, tin at 1:1 ratio.
7. a lot of orc society revolves around the movement of coins. you need bonemold coins to raid, raids earn you coins in silver and gold which get dumped back into bonemold coins. you need coins to buy certain things to advance your base, such as seed packs for the orc fort only crops that are used in making colored bricks from clay which are magma safe.
8. it takes a lot of work to understand the system and the incapacity to revert the coins into lesser coins, leave some players high and dry when they need say copper coins or silver coins and their entire stock is in bonemold and platinum.
9. In the base set up you can't mint bonemold coins at a forge.
Dwarves and Humans are very different.... most people don't even get involved in the dwarven shops, other then minting coins for guilding characters. I personally don't have a lot of experience with the dwarves.
Humans have only 1 coin in their setup and a voucher system. They have I think 15 shops(don't quote me its been a long time). I just remember I could make a square room 25x25 and all the shops + a depot would fit around the outer edge leaving a 15x15 space in the middle. I'd ring that with 3x3 shops then I'd have a quantum stock in the middle 9x9.
basically if you can buy it with a coin it generally sold at 1/2 the price unless it was considered "common"... the common items could be traded 1:1. generally anything purchased could never be resold at better the 1:1. you could sell or buy just about anything, but for somethings a voucher system would become involved.
vouchers would be a tool item made of the same material as the item sold, so say you sold a copper sword, you would get a copper voucher, well if you bought a sword it would cost you 2 vouchers, and the material of the voucher determined the material of the sword. you could directly buy certain material vouchers at set coin prices(I believe they were gold coins). basically with enough raw materials to sell, a player could eventually buy decent military goods and equip an army... many human players will wipe out an entire forest and sell it, then dig an open mine, sell the stone, wipe out the new growth forest, fish out the rivers and ponds, create huge ranches, etc. just to produce raw resources to produce goods.
the main thing coin is used for in human societies though is the guild halls. a lot of coin gets sucked up in building and purchasing permits to build up the various guild halls, each hall has 4 special shops that require permits to build. these are then used to produce large quantities of goods at rapid rates.
there thats all the knowledge I have for you.