classic motorcycle forum

Hi FordMoster,
It´s quite hard - if not meaningless -  to give any estimate on price-ranges on vintage bikes. Type of bike, year of delivery, matching frame- and engine-numbers, authentity (carbs, tank, frame, seat etc etc) and quality overall can make the price vanish to nothing or can even drive it up to any price if in showroom conditions. In Dutch (as I am): It's what the crazy guy will offer that makes the price. (There's probably a better English idiom for this, but I ain't got it at hand...)
Anyway: with Internet (Google or so) searches you'll get quite some indications of prices of the bike you're going for, and various auction lists might get you on the way for any give BSA, Norton, AJS/Matchless, Ariel, Velocette etc. E.g.
http://www.practicalclassics.co.uk/auction/by-id/1036274656/   (or equivalent auctionlist)
http://www.cotswold-classics.co.uk (look for “stocklist” in the top)
http://www.classiccarsmagazine.co.uk/auction/by-id/1945836131/ (or equivalent auctionlist).
I'm sorry I can't do any better. Good luck.
RIVO (Norton Domi mdl 7 & German bike owner)

Thanks for your input, I really appreciate.
I will look it up ASAP.