Can you explain why that is? Does the 7770 perform better sans AA, but the 6850 without? And I have been taking a hard look at the 6850/70. Here's two I found for a good price on amazon.
6850 for 135-15mir = $120 (newegg had it for the same price up until about 2 hours ago for some reason, they change their prices too often for my liking, its screwed me over a couple times when I thought I had what I wanted all figured out)http://www.amazon.com/Sapphire-Radeon-PCI-E-Video-100315L/dp/B0047ZGIUK
6870 for 167-20mir = $147http://www.amazon.com/dp/B005C31F2M/?tag=pcpapi-20
(Edit found another cheap 6870 on newegg, considering I can do the free 2 day shipping instead of paying 8 bucks, but it doesnt get good reviews and I don't really care about the free game)
6870 for 160-20mir = $140http://www.newegg.com/Product/Product.aspx?Item=N82E16814161389
Good prices? I always take the mir with a grain of salt, since most of them almost seem like they are trying to scam you out of it. Leaning towards the 6870 since 30ish dollars for 20% better performance seems like its an ok trade off, even if some would consider the 6850 a better value.