Hello Eric,
Apologies if this appears to come over as opinionated, but the strong vibe I’m getting here is that you think the seller is charging £500 too much for the car, and you are looking for advice on whether the car is worth the asking price.
Unfortunately, I cannot see you are going to get sound advice on this since no one on here has seen the car to appreciate its true condition, and the ‘valve for money’ can only be judged by a thorough inspection.
As Steve says, it’s now a seller’s market, so if it is what you want, and you can afford the asking price ( with some in reserve for yet undiscovered issues) then you either choose to buy it, or look for another one for sale at £3,500. Sorry Eric, but it really is as simple as that - unless the seller will offer you something off.
To me, guide prices are just that, and for me, a cheap car is just that, and one in superior body and mechanical condition becomes far more attractive and worth a premium. Only you (and/or a paid-for independent inspection) can truly evaluate what the car is worth - to you (in caps).
It is worth noting that condition is remembered long after the price has been forgotten!
Good luck with whatever you decide to do.
Kind regards,
Gareth.
p.s. My view with cambelts:- change every 5 years irrespective of mileage.