go for the one with the mail in rebates. Cheapest one I've seen so far is $249.99 (after rebate and before any tax). It was for the XFX one but since then the price has gone back up
I think the above link would probably be the best bang for the buck, as it as a higher clock speed than the other 8800GTS that they have, and its only 15$ more than the lower end one...