Agreed. Wait until the i5 3570K releases, certainly worth the extra little as you can overclock, slight performance boost over the i5 2500K and lower tdp and higher efficiency.
As for $850 check out my $850 build here:http://www.squidoo.com/electronicandmore
Gives you SLI/CF @ 8x/8x on the motherboard, you get a PSU that would be plenty for Crossfire and SLI and the 7850 which is a great card. I'd just switch the i5 2500K with the i5 3570K when it releases.