Not all Vincents are the same
One of the challenges I see in Vincent pricing is the same as in another of my hobbies, Toy Trains.
When one item sells for £50, then the general public automatically thinks that if they have one the same (type, colour) then it is worth the same money.
What they fail to take into consideration are things like condition, provenance, originality, variation, rarity and the like.
I see just the same happening with Vincents - a nicely restored (with some expensive bills) Rapide sells for £25K and automatically everyone thinks that the rather tired, heavily modified, non-matching numbers with no paperwork bike they have is also worth £25K. Then to pour petrol on the bonfire, someone agrees with them and pays the money - ouch!
Not sure there's an answer, in a world where supply is strictly finite of original machines and demand appears to be constant or growing then logic/economics/common sense would all say that the price of buying one will go up. Note I didn't say value.
The new Black Shadow got some super coverage in both mainstream and classic bike press, I wonder if there was a "spike" in membership enquiries following that, it may well have spurred people on to have an interest in owning a Vincent as a result.
Hopefully when someone comes a cropper and buys a wreck by mistake they'll need to write a very large list and come looking for the bits to make it run Russ - it does look like there are still some poorly Vincents out there.
Stuart