Almost any MMO with an economy has an auction house these days (A Tale in the Desert excepted, for special reasons). Are we to the point yet when buy orders become standard? That seems like something the next set of games needs. A few of the current-generation games have learned the basic lesson that the economy functions more smoothly when you have parity between buying and selling. EVE Online is the best example; steal their economic tools. If that seems like too much for you, look at the City of Heroes consignment house, which is a simplified version of the same thing. Yes, City of Heroes, the game with no equipment as such and where crafting was added years into it, has a better economic system than your game.