Hey so I'm being extremely picky about the computer I finally buy. I was trying to lower the price on this computer as much as I could but I'm not sure if I can without lowering performance or upgradability. Heres what I have for my gaming PC build:
Start with the Stock cooler on the 2500k. You can always upgrade to a better cooler if your OC is being Temp constrained.
Drop the SSD. You can always upgrade to one later, or get a 64 GB SSD.
Your system is not upgradable to SLI anyways, because of your power supply. So you can get a $60 p67 board, or a $80 micro-atx z68. This is not much savings, but the upgrade from z68 to z77 is not very significant performance wise, especially since you are getting a SB CPU.
I dont see RAM in your build. Not that you can save much on it, but RAM speeds dont affect SB performance much, and if can pick up a cheap 1600MHZ set of 8 gigs instead of higher speed ram.
SLI is sticking 2 identical Nvidia graphics cards into your computer so that they run together. Ususally two cheaper cards linked together would give you slightly better performance per dollar than a more expensive card, but you have to deal with increased power needs, larger power supply requirements, more heat and a bit of image quality loss due to flickering shadows etc.
Your power supply is fine, but its 500 W, so you wont be able to do SLI or Crossfire(same as SLI but for AMD cards).
So if you dont know what SLI is, I suggest you stick to a single card config. This being the case, you dont need the extra pciE slot on your motherboard, and can get a micro-ATX board with fewer pciE slots for slightly cheaper ($20-30)