Well, as said $400 isn't much, even though I have no idea with $:£ anymore.
I brought a cheap Gigabyte motherboard based on P35, an Intel Pentum E2180, 2GB PC2-8500 RAM and a Samsumg F1 HDD (great drive) for just under £200, which, I think, is about $400 now. Now if you use the components from...