I did a google and could only find used but found new ones via ebay directly from 450 to 675.
It is not irrelevant, if a garage wanted to replace an alloy with a genuine one but slightly cheaper then they can. If I know the original price then I can judge what to advertise it at.
Its a wheel for an old car, you need to have it compete on eBay with used ones targeting people who have broken a wheel, etc. It'll need to be very reasonably priced. You'll achieve a markup over a used one, sure, but not much given the car that it fits?
This is like me trying to sell a 5 year old proliant server for anything like its 5 figure original price tag Good machine sure, but who wants it!