I certainly can’t agree with that idea ! Recently I sold a very nice Bonniksen speedo, complete with drive gear, gearbox, etc., on eBay. I would have been happy with about £1000, but it fetched a staggering £2600, a sum entirely a consequence of what buyers were prepared to pay for it.
In a similar vein, many thousands of bikes, cars, antiques, collectables, etc., are sold every month at auction WITH NO RESERVE, so again the selling price is entirely a figure decided by BUYERS, not vendors.
Brian