It's all very well for a dealer to 'value' a car at what it cost the buyer originally, X number of years ago, but unless the dealer buys it from you for that figure there and then it means nothing.
They'll more than likely want to sell it SoR, in which case there will be commision due to them and any costs incurred to prepare the car prior to sale. All this adds up to quite a few thousand pounds.
The usual SoR situation is that the dealer puts it on at an 'optimistic' price to massage the ego of the seller, then after a month or so with little interest, the price drops start, or it just sits there for ages which helps no one. The buyer gets more an more frustrated and the dealer looks inefficient because their stock is sitting around for ever looking stagnant.
As Deejay points out, finding a buyer is the current problem for dealers.
There just seems to be a lot of cars for sale at the moment....🤷🏻♂️