I played WoW (World of Warcraft) and PoE (Path of Exile). WoW's auction house is mandatory for making gold. You don't just have to price an item with 1 gold lower than the last guy who posted the same item. That's why there is an Add-on for statistics with profitable / non-profitable to invest, average sales in a week about every item, resetting the market risk etc... It's not simple, so the ones interested in marketing are doing LOTS of gold and the ones who still need the gold, but they don't have this financial spirit have to pay real money for lots of gold. Balanced for both type of players (except the poor one I guess... I was one of those who was permanently selling things). In PoE the AH system is not implemented in-game, but they made an official site for it. The PoE's economy was never destroyed, yet they used the AH system for a long time.