I once purchased a lot of 20x dual-Xeon (1st gen) DELL servers from a liquidator on eBay. They were extremely cheap. The seller personally delivered them in a van on a four hour drive because that's what made financial sense due to the shipping weight.

They were fun to play around with and it was definitely an experience. However, having them around became old quickly and flipping them was much more difficult than I had originally thought. Luckily I ended up breaking even, even after personally delivering a few of them several hours away.