Some guy ripped me off some bucks, I was wondering is there anyone who deals with those things? [SORRY IF WRONG SECTION]
Please report him to MODS. You can find MODS over here: http://forums.digitalpoint.com/showgroups.php
I don't think mods can do anything about it. Leave them a -ve itrader to prevent other users from doing business with them. Other than that there's nothing you can do.
No - I'm afraid it's caveat emptor (let the buyer beware) here, as in Real Life. Make sure you leave them negative iTrader, to help protect others. If you can find the original DP thread, bumping it with a report of the scam is also considered fair game.