The market system is pretty straightforward. People don't like dealing with complex markets and that's understandable, but a straight auction house for everything is a step backwards. Usually those imply a cost for just listing something, which usually strangles ingame economies. Items with lower demand never see the light of day in those systems. If there was an aux. auction house, as for selling off rare or very powerful HQ items, it could add a certain amount of interest towards both sellers and buyers. Replacing the system we have already, though, would just prove detrimental.