It is always advised to get a single video card if you can get anywhere near the price/performance level that you want with it. Crossfire software has improved a ton, but still simply has more challenges than a single card - including more heat and etc.
The PSU seems to be out of stock. You don't really need a PSU that large anyhow - even for crossfire. Id suggest the Seasonic X650 gold as a way to maintain the same level of quality - just cutting 100w. (I have it - its a fantastic and silent PSU)
Finally .. do a quick scan of the deal sites (techbargains/logicbuy/etc) and newegg newsletters. You should be able to get some rebates lowering prices. In particular, I think that you should be able to find the 128gb Crucial M4 for $89-99. 64gb is barely large enough for a boot drive and not a size I would go with in a higher end build.
1. Microcenter has great sales on 3570k & MOBO for just under $300 with tax
2. May want to consider ASRock Z77 Extreme 4
3. I would not go below 120 GB SSD ( I love my intel 180 GB !!)
4. 3570k for over clocking, but not CPU cooler. If not overclock i would not get a 'k'
5. I would go for the HD 7850 (x2 if you got the cash). If you don't have the cash, I'd buy one and wait for the other - there's always Christmas