Is it possible?

I've been looking on ebay and have found some in the $400-600 range that seem to look good. I've just been so far out of the loop on pc building. The last machine I bult was an FX55 machine. I still have pieces of it laying around and I bought another machine a few years back and have pieces of it around too. I have 3 hard drives that I could throw in it and a 750 watt power supply. No monitors or anything needed.