Feedback goes a long way, just for the extra reassurance for other members if its possible to add a feedback option to a members profile. I use to play paintball and on they have the feedback capability. If this is too much trouble, maybe make a separate thread/section for feedback. A user can just have their own thread with their name ("rain91 feedback) and after dealings have been thoroughly finished users can post on eachother's thread for how the deal went. Pretty much like ebay, A++++ would def do business again.