Then there's the definition of 'classic': as it left the factory or re-engineered using modern technology to make it everyday usable - do you want to look at it and smile or ride it somewhere?
Read a Classic Bikes article by a guy who had an open cheque restoration done on a T160, 3 pages dedicated to the 'as per the factory spec rebuild' then the last para with the owner becoming disenchanted as all the original short comings of the faithfully restored classic came to life. Having had a T160 new in 1976 I could sadly predict the outcome: the inconvenience of a thirsty bike with a small fuel tank, a clutch cable that couldn't handle the clutch (need for a left hand that could crack walnuts unaided), clutch prone to slip, starter motor unreliable, started to smoke on middle cylinder within 1000mi, spokes on rear wheel unable to hold tension, carbs going out of sync because they all had their own stretchy bit of cable etc. Oh how I laughed. I replaced my T160 with a Honda 550 Four K3 which suffered a filament failure in 36,000mi ~ and nothing else.
Want to smile and ride round Europe, then choose carefully or be prepared to own a stable of bikes!
I guess there will always be a demand for the 'right classic' so may be there will always be some form of bubble!