I bought one of NASA MSFC's old "mainframes" a few years ago, just for fun. It was huge and I didn't have three phase power so I was never able to turn it on, but it was cool to take it apart and examine all of the cards that they were using, and see all of the engineering and design of a million dollar computer. It was an SGI Challenge 10000XL "Rackmount" that was fully loaded, I paid $25 for it. It was utterly huge, it was the size of a refrigerator and the weight of a small car.