$400 will get you a lot of stuff. But I didn't know it would buy you something as cool as this. You're looking at the case for a Cray EL98, in its time a $six-figure, 700+lb behemoth of a machine. Now sadly missing some of its whirring, clicking innards (i.e. it doesn't work) but with a custom, museum-quality stand, its current owner has decided to part ways with the charcoal number-cruncher and make some other geek's case-mod dreams come true.
Alternatively, you could buy it, take out what remains of the original wiring, circuitry and other electronic mischief (photo after the jump), and move in. With property prices as they are, it'd probably be the easiest way to get on the ladder. You've got 'til midnight Thursday to make your mind up (and locate a forklift truck).