Still another way to handle it would be to have a gentleman's agreement with the players that they're free to make all the money they want, but they promise not to pour it all back into magical items. If the PCs are using the extra 80% of cash to build castles, buy titles, bribe mercenary bands, and such, then that's good for the game. That sort of thing is interesting and it's good that they have 'extra' wealth to spend it on. Too often in 3E I saw PCs who were carrying a fortune in magical equipment, but never spent cash on anything else other than a superior grade of inn. I recall a DM once pointing out that we were basically homeless bums (who happened to be rich beyond measure).