This sounds harsh, but even if I spent £1000 on doing my Golf, it doesn't make it worth a £1000 extra on what I paid for it.
What one party thinks something is worth is total slantant to who's selling it to you.
There's nothing in the world that would let me part with more that £500 for a 20 year old Golf. Yeh they've got character and there old fashioned mechanicals so easier to fix - but there nearly always something to fix on older cars.
The more classic the car, yes the more it's worth. There's no way a MK2 is a classic. it's an everyday driver, rugged and handy in the bendy bits. If it's a car you are only prepared to drive when the suns out in the summer months, and put it to bed and tuck it in the garage - that's a classic normally speaking.
£3500 for a MK2 GTi - 16v I pressume? it it will only be worth the trade price which is for a 20 year old Golf about £200-400 to a dealer who doesn't want it - and will end up in an auction in Southampton Docks or the like. and sold for peanuts to a stockcar team.
I paid £550 for a solid 1990 "H" 1.6 driver but very convincingly looks like a well modded GTi. I have spent a small fortune, putting it right what some kid done to the car mechanically. Realistically I will have spent another few hundred quid on it in parts alone since I have owned it, to fix the neglect, but I wouldn't value it at anymore than £600-£650 with a new MOT and tax which I didn't have when I bought it. It's worth this to someone. I just bought it to get me through the winter only
When I was 17 I thought putting alloys and exhaust on a Mini added value? it doesn't my dad was right.
I wish there was nowhere online you could buy car to be perfectly honest! It has ruined the used and classic car market. If one bloke puts a Lotus Cortina on for £10K so does the next making his £11K, and the next making his £12K and so on. it has made everyone very greedy indeed. If these were compeating businesses this would be racketeering. This is what estate agents have done to house buyers. Then people wonder why when they crash that £12K Lotus Cortina they are only paid £3500, it's because of where they bought it ramped up the prices bases on everyone elses price and so on, and so on, not it's true market value. Most things you buy things on impulse and your emotions and desire get the better of you.