Yep, eBay is booming with second hand workstations like this. Cousin bought a HP Z210 Quad Core E3-1270 3.40GHz with 16GB RAM for 320€. Added a SSD and cheap GPU and is an awesome 500€ machine that can last for years.
Totally there. If your electricity is cheap, it's an awesome deal. Since, oh about, 2009, there are a lot of choices that are akin to buying a '57 Chevy.