it will be 110$ more expensive with 2xHd7770 OC edition But i won't plan on buying both at the same time ~ I would save $130 from getting the 7770OC then the 7850. but would crossfire the 7770 soon (don't want to completely empty out on wallet )
More aboutcrossfire hd7770 single hd7850
Dude... That's really expensive
Get the 7850 .
2x hd7770 is better 1X hd7770 is actually quite good but 2 is very good as they scale at 90%+
the fps difference between a 7770 at 1200 core 1400 mem is 5 fps compared to reference clocks. So, with that, you can get nice 1100-1150 core and a 1300-1350 mem clocks with the card i linked, you will be only missing out on a few fps, but save money and get the best bang for the buck at that price point.