I agree, although you don't necessarily NEED 2/3 gpus, but it wouldn't hurt. I have 6 gb ram, and my computer feels fine, you can cut some corners to mark the price down. As you spend mroe and more money it seems like you get less performance, but don't cut too many corners
But yeah, you can build yourself a ncie computer for 1,500-2,000. Do your research though, I spent a long time reading up on motherboards, etc, comparing prices (some sites have good/bad shipping, discounts, rebates, etc), reading several guides on how to build so I didn't mess up (mess up the cpu, and you're down a lot of money). but yeah, there are magazines and guides on-line that were about building your own computer and they'd have a recession article, a medium range article, and a really expensive one. As I said, just do your research and you'll figure out what you want.
And I built a desktop...I'm not familiar with laptops, if that's what you are planning to do...although I tried looking for a gpu for my laptop and had issues, so maybe building laptops isn't very common.
i bought a lot of my stuff off newegg, but when I got my defective 40lb case...they could replace it, but gues who has to pay shipping? 40lbs is expensive. try to find places that will give you a full/partial shipping refund. a lot of computer parts reviews turn up less than perfect because people get defective parts (i read a lot of defective reviews on RAM). I got lucky with everything else other than the case ;)