Dunno about in the US, but the pricing seems off for these parts in the UK. The 5770 is okay, but just isn't competitive enough with the 4870/260 which are the same price or less.
The pricing here is:
< 100: 250/9800
There's too big a jump between 5770 and 5850 in price/performance and the 275/4890 are too dominant here.
*note the 5850 is massively in demand here, and the sweetspot in price terms so over inflated. I think the etailers are gouging on this part, and hoped to gouge on the 57xx series also - but aren't shifting stock. The 5850 is bundled with 2 games @ £30 retail, the 5850 none.