Small idea to have people that will use markets and those that prefer not to. You could have a universal broker that would allow players to get in and out of the system (*note broker ideas really only works well with a mailing system). You would restrict players from only being able to put up many things. So lets say 5 things. Each of these 5 things are then available until purchased. To give players an incentive to go to the market the broker will add a large markup. Now this indeed punishes the less wealthy players but in turn they are also sinking their money back into the game and not to players. So the whole system will only assist in speed but everyone looses in the transaction. So it will work just like a real pawn shop supporting people focusing on managing their market.