If its a good un (which it almost certainly will be!) then £20k is a fair deal IMO....its just such a rare bike.
Is the bike in italy the one with under 1000km on the clock and billet calipers etc..?
I think I mentioned before but I know someone who bought one about 6 years ago and its soared in value.
The only thing I would say, is that I think its one of those bikes which should only be used sparingly as a second toy to keep the mileage down and its condition mint....in the same way a Ferrari enthusiast wouldnt buy a GTO and use it every weekend I guess !
Oh..and like Rob..let me know about the second one as I know someone whos been looking for ages too !
By the way..I picked up a bike book from on outlet village cheapie bookshop for a fiver with a nice write up on the SPS (and other exotics like NR750/NC30 etc)...its called superbikes by Roland Brown..ISBN 1854224026...
Cheers
Nat