On other forums I peruse, especially gun forums, there are features built into the user profile pages that allow buyers/sellers to rate each other on their transactions. It allows other members to get a feel for how they do business.
Another pre-requisite for participating in buying/selling is that your complete contact info (phone, email, address, etc) has to be "on file" with the Admin/Staff/Moderators in the event something like happens.
I would not oppose and would even prefer that this was the case here as well for those who trade in the equipment exchanges.
I've had good luck on here and AS, both buying, selling, and trading. I also go back to the thread and post a comment on how the transaction went down with the hope it helps a fellow member decide whether they want to do business with me or them.