It's a lightly modified 2008 Mac Pro. It's kind of weird, but the specs and condition (that I can see from the pictures) are actually okay for the price they're asking. And free shipping on a forty-plus-pound tower is a great deal in itself.
I don't know, buddy. Ask the seller some questions. Personally if I had two hundred bucks and needed a gaming PC, I would buy this. If this won't be your main PC, I'd say go for it without question. eBay often sides with the buyer in disputes, so if it gets damaged in shipping or doesn't work there's a good chance you'll get your money back.
Also (and this is basically irrelevant for practical purposes) that PC has better build quality than pretty much anything you can build with off-the-shelf...