Anyway, if it's so cheap why not just get it serviced straight away? Jobs a good 'un! If it's been abused previously you should be able to tell by looking at it anyway
What do you want to know? The Bostrom should come with a stand (blue), cover and a metal plaque in a blue box as part of the package, which I guess will be missing.
Obvious differences are blue frame, blue wheels, Ohlins front and rear and damper, and plaque on the yokes with Bostrom 998S x/155
Price wise, well I'd say a good one from a dealers with service history will be anywhere between 10-12K for a 2002 plate dependent on mileage, so 8.5K doesn't sound bad I guess first thing I'd do would be to get it fully serviced and checked over by someone good though.
As for a bike still the best bike I've owned once set up, although I expect the 999R to take that mantle shortly as the miles pour on.
The stand is only the box standard stand just painted the same blue as the frame, so you could get a standard one off Ebay and get it painted I guess.
The cover is unique to the Bostrom red/white/blue with 155 and his signature on also, but I would imagine you could order that from Ducati, you can order the graphics kit so I guess the cover should be available also. As for the plaque and box, well I don't know about that one, each one is unique and engraved with Engine/frame number and corresponding number on the yokes.