Go on ebay and buy a new 5770, it has the same chip as the 6770.
I saw some for 70$ last week, but they were gone in 30mins.
Just keep on look out, they always show up.
I'd sat get this one http://www.newegg.com/Product/Product.aspx?Item=N82E16814102873
100$ after rebates, and it has good cooling, and won't make your system look like crap.