Well I bought my current CPU+ram+GPU+HDD+PSU off there without getting scammed
Also there an iTrader system in place so you can be confident of your purchase by looking at the feedback the seller has been given.
And if you ever are in an unfortunate situation then there's a dispute/problem section where the moderators will take necessary action on the forum and help with legal action.
Nobody should be breaking the rules and it's common sense not to buy from a new user
Unless they send the item first ofc
http://www.avforums.com/forums/view_trading_rules.htm