It's economy is going to fail like almost every MMORPG economy because they only cover the supply side but not the demand side. Since every item is a commodity which is mostly obtained incidentially there are a lot of sellers that sell low quantities of that item. They don't care a lot about losing a bit of money they want liquidity. there is usually a limit on simultaneous sell orders which means you cant sell anything at all if you don't prioritise liquidity or have high quantities. The easiest way to quickly sell your items is to just price your item lower than everyone else. When everyone is doing this the value of the commodity is quickly plummeting far below the price most buyers are willing to pay. Heck I've seen items that cost less than the money NPCs would give to you (premium users can access the market place anywhere outside a city and they dont want to go to the NPC) This gives rise to traders that buy these cheap commodities and then sell them for the market clearing price. The simple solution would be to just reflect the demand side as well. Allow players to issue buy orders like "I want x of item y. I pay z for each." on the central marketplace. Those who need liquidity get it and those who want fair prices to sell their items at get them too.