[Yahhoon23]

Edit: Nevermind, I saw your edit.

Also, I don't see how letting them allow to discuss transaction addresses etc in PM would be a bad thing.

You can have them discuss all their trades, prices, negotiations, etc in their threads, but just have them send each other addresses etc via PM.

As for someone signing up and giving themself a rating, if you use the conditionals he provided for only being threads that are in x forums, then use a promotion allowing people after x amt of days registered or x amt of psots to be able to see the buy/sell/trade areas that stops people from signing up to boost their feedback.

Without using that option, the best you can do to prevent people to do that, is just make examples out of people and ban everyone who does it.

I have moderators that will be checking ratings whenever they feel like looking, and if they see a fake thread or fake feedback, that user will be banned permanently on the spot.