So I was browsing reddit today and I stumbled upon this build, credit goes to /u/bpgt64. If you choose not to buy Windows, then the cost of this build is kept under $500, a true kill-your-console build. The one problem I have with it is the graphics card. IMO it'd be better to have it replaced with an AMD card such as the 7950, a card which we have seen go for as cheap as $180 after MIR. But in all honesty, which graphics card to get is a decision left to the builder of the system (just like everything else). Anyways, here is the shopping list if you buy it from MicroCenter:
Looks great except I would feel a bit weird about the ram, I personally would go 8gb's and there no reason not to go 1600mhz but otherwise cool