User blog comment:Old Deus/The Shop System/@comment-13970942-20140326223704

Setting prices could be tricky. Scarcity of resources, demand and whatnot would modify prices, but having these arbitrary prices reflect that seems like a demanding task. It's also somewhat unworkable, since as yet users can still just add currency to their characters.

Rather than tracking individual coinage, I have seen some systems use a "paygrade" system, wherein a character has a wealth ranking, which determines their approximate income on a monthly basis, and from that can determine the relative purchasing power of a given character.

d20 Modern (a d20 supplemental book for the d20 RPG system) expressed this well, I think. The Fate RPG also had a relatively simple system for tracking buying power. I would suggest either be used, rather than counting coins.