this is the classic bike world today. the bike community has spent 20 years riding stuff that they havent needed to lay a spanner on, nobody learned to fix anything, so anything thats remotely non stock becomes premium priced, sidecars are tricky to fit and set up, its not rocket science, just basic spannering, but we live in a world where people pay dealers to change light bulbs and are incapable of replacing a spark plug.
having said that, i wouldnt give them 8 grand for that thing if it was running and mint, ffs its a 1970 ducati 250, its not like its a moto giro eligible 50's bike. they will have that on their site for a decade if thats the price thyre set on.