They come up on ebay all the time, and uk.comp.sys.sun and uk.adverts.computer occasionally.

I've been meaning to get one myself sometime - purely to have a computer that cost megabucks when it was new - I've got an sgi Indy in the corner at home but unfortunately it switched on a couple of times and then I think the lithium battery in the RTC zonked out. At £20+ for a new one I'm waiting for a motherboard to appear on ebay.

Gareth