If you fancy buying a decent bit of computing power you could do worse than bid for a Cray Y-MP C90 which is listed for sale on eBay.
Bidding opened at $35,000 and has now jumped to $43,210.
The machine is called Mario and is described as having been the world's most powerful supercomputer seven years ago. It's in good working order and capable of 16 GigaFLOPs and you don't need security clearance to buy it.
The sellers describe it as an extremely reliable workhorse for R&D computing. Mario, a black and gold beauty, contains '16 vector processors, each capable of 1 GFLOPS performance, main memory amounting to 512 MegaWords (4GB), and a 512MW (4GB) Solid-state Storage Device (SSD) serving as an extension to memory. He comes with raid controllers and disks providing over 130GB of high-speed disk storage.'
You can bid for Mario here.