Why don't you use a proper market site like http://www.tradehill.com?r=TH-R117037
Trades are going on automatically here, so nobody can cheat, and you do not have to manually transfer money or bitcoin.
This also helps to avoid mistakes of both sides of the trade.
You also do not have to wait for your money or bitcoins, since the trade itself is done automatically and the money is transferred into your "virtual bank account" on tradehill.
Sure you have to pay a small fee per transaction but think how many time and annonyance you save..