HoML does it. The PCs start with X amount of gear (like in 4e, there's a list with associated costs and they get 100sp to spend). From then on their wealth is basically abstract. They might, narratively, find '1000gp', but there's a simple chart that shows what fictional amounts equate to 'trivial', 'significant', and 'great' wealth/expenditure. The basic assumption is that treasures give the PCs 'significant' money, they can achieve significant expenses in the ordinary course of play, possibly with a check required, but not a really difficult one. If the fictional positioning of the game results in a PC becoming separated from his wealth (IE losing all his goods) then he's going to be stuck scraping to make a 'trivial' expense, but normally those are just assumed. 'great' expenses are going to require the characters to pool all their resources, or obtain some unusually rich source of money, and will require difficult checks. Its possible some PC might find this kind of check within his modest reach if, narratively, he's focused on and insured that he acquires wealth as a specific asset (this would probably constitute a major boon in my game, the equivalent of what you gain for going up a level in 4e). It does work. Clearly if the players are going to try to break that system, then the GM will have to push back, but I've never seen that be a real problem in actual games.