I believe there already is something very similar in place, but it doesn't work quite right. The prices for individual items is adjusted by nobles frequently after the economy starts. However this in no way takes into account the number and availability of they quality types of each item.
Something that I see that doesn't make sense is that a dwarf can take a break, but he does none of his recreational tasks on a break. Tasks like picking up new clothing that is not job related, or purchasing stuff, etc should be done on breaks. They should not count as a job related task. I hate seeing a dwarf that I need to do something NOW stop to take a break, sit around for 5 mins, then trade out 3 pieces of equipment, go to make friends, etc., all before he decides to start working again. That stuff is what breaks are for. This should help dwarves recieve more pay on average too such that they can afford more of the finer things in life.
Finally, coins. Ahh coins, the bane of every player's existance. Dwarves waste time dragging single coins that they've earned to and from their coffers if they're lucky. If not, then their workshops, hallways, and stockpiles are littered with coins throughout the fort. I can see a dwarven fortress, where pay is determined by the price of goods, and the quality of work, and is paid out through a new noble. The Paymaster. When he arrives he forms a squad of workers (name?) that you can assign a worker too. These dwarves will assist the paymaster in making sure that everyone has the correct amounts of coin for the work that they've done. There will also be a new building, the vault (humans and elves would have banks), for those dwarves to store coins that they have nowhere else to store, and it will be run by this squad. Of course recombining stacks of coins would be wonderful in helping out this problem too, it would reduce the number of dwarves needed to devote to this greatly. Also would giving the dwarves purses, where they can carry coins on their breaks in order to make purchases.