There's a snag, of course. It has apparently been giving problems accessing memory cards (it uses CF cards) and the owner decided it's not worth trying to get it fixed, since it's a fairly old model and "only" 6 megapixel. My research last night suggests that this is a fairly common problem, with several possible causes and solutions - at this price I'm happy to see if I can make them work. I've tried it without a card and everything else seems to be working very well, unfortunately it doesn't have any internal storage without the card so I can't actually check the sensor works, but the rest seems fine, my lenses autofocus on it, etc.
Needless to say I don't currently have a CF card - my last one went when I sold my HP Jornada - but Ebay found me a 4gb card from a UK seller for £6.26, so hopefully I'll be able to check this out properly at some point in the next few days. Then if it turns out not to be repairable by me I think I'll just sell it for spares and repair - doubt I'll lose much by doing so,