How much would I need to spend for a good gaming computer?

I am looking to build a solid gaming machine, something that can run some of the more intense PC games on high settings with little to no problem. Games like starcraft 2, dragon age, etc. I don't necessarily just want to be able to run them on highest settings, but I want to run them on no settings with no problems at all, so that more intense games in the future can still be run very well. If I were to buy all of the parts to make the machine myself, about how much would it cost to make a computer like this? Just a general estimate would be great.|||Check out this great website http://www.pc4game.com/ .|||1000-2000 if you build yourself...about 1500-3000 if you want a decent comp to buy which you install the hardware yourself...3000-4000 for a pretty good already made one.