Aye John B,
One 500cc in the Island at Ramsay Motorcycles offered at £2,800 during 2004 Manx. Complete with service tools and a spare set of complete wheels. An offer of £2,500 cash would have secured!
Bat motorcycles had at least 2 x 350cc and 1 x 500cc not long ago. They disappeared and then appeared to re-appear on NLM's website with a 'mark-up' and then sold quickly. Were still displayed on NLM's site when last looking with 'SOLD' through the image. Possible reason for this is that BAT will source them in Japan to fill the container, as that was their main export market. Few, Nuovo Saturno purchasers will visit BAT's site and NLM's site attracts them like bees round a honey pot! ;-) If BAT are selling a 500cc for less than £2,000, with warranty, go on!!! ;-)
I know of one 500cc up here, that went 'Pop'. A Nordwest motor was popped in and more fun was the result. What mods, if any were required and whether it is still running will require some discrete enquiries. A Nordwest circulated in the Manx a few years back and was no slouch.
Bob Wright Motorcycles I believe, can supply most running spares for the beasties.
Cheers, Bill.