A heads up on the 7850's. It looks like best buy is clearing their stock so a lot of stores have 7850's on hand in clearance for $107 per. So, a little over $0.28 per kH/s. Might be worth checking your local stores.
I checked my local stores clearance and open box inventory online and they don't have any. I even called and got a sales associate that just told me to come into the store, I guess he didn't want to type to check inventory. Bummer, I would have bought at least 2 more and got a couple powered risers and hooked them up to a spare PSU.
BEST BUY SUCKS!!!