Why not buy a Gigabyte 670 OC Windforce new? I purchased one on Sunday for $457 from BestDirect, taxes included. If you don't want to pay extra for shipping, ground shipping is free. Bought from them b4 without any hassles. While this isn't a jaw dropping deal, everyone added a premium because of demand. Suggested retail is $399, most stores have added between $10-30 or more.
Check out the review on it. Keeps up with both the 7970 and the 680!!!