Ant- Ebay! Ive picked up a few silly bargains like that, I got hold of a brand new GT60 with a .86 exhaust housing for similar money once, but no fricking idea what to do with it, even tho they normally retail at about 2000quid
Best thing is to search for "enourmous" "huge" "gigantic" and "turbocharger" rather than "turbo".
These are usually sold by folk who arnt nececarilly in to tuning cars and also ones who think the turbos are so big they useless to anyone.
I got the Holset so cheap as the guy was convinced it was a 1500bhp turbo that wouldnt spool up till high revs even on a big V8. In reality it would spool fairly ok even on a 2litre...