I've sold 4 CB750's in the last couple of years, prices as follows:
1970 K0 (running, unrestored but rough with lots of K1 parts) $7500
1972 K2 (mild custom, "Goldie" BOTM winner) $6500
1973 K2 (restored to original, BOTM winner) $6500, and
1977 F2 (restored to 90% original with K6 top end) $3750.
I could have held out and gotten more on a couple of these bikes, but as I'd built all but the K0 from parts or junkers, I was happy.
I grudgingly agree with Lucky's concerns regarding buying a bike that's been laid up for many years, while at the same time I'm happy that my 1980 Honda CX500 that was laid up for 14 years has suffered none of the problems that he describes, although the brake MC seal was buggered and the front calipers were both partially seized after all that time.
Obviously a major service would be mandatory, which would have to include a thorough oil and filter/oil pump screen change, brake overhaul with new hoses and seals, pads, etc, fork seals and oil, air filter, plugs, new tires and tubes, chain and cable lube etc.
Or, just park it in your lounge room and look at it..........