I think GENERALLY, it’s better to buy on condition rather than mileage. But with these cars, it’s better to buy a very good example and pay the extra. Volkswizard on YouTube even says, he would rather buy a very nice standard GTI than an okay health edition 30.
https://m.youtube.com/watch?v=uJfdODbFTUwWith these cars having their relatively rigid servicing schedules, I’d really want to know when things have been changed. You might be able to check the dates on some parts like the battery and coil packs? A keen self service owner would surely have replaced these.
Do all the usual checks, as you’ve taken it for a test drive and you should be able to hear, feel, see if it’s a good car. There’s plenty of GTIs that make it to big mileage, no reason why they can’t as long as the servicing is done on time.
It could be a case of more chew than it’s worth with the mentioned suspension/engine components wear posted by others above. About the aircon, I’ve just had my aircon diagnosed and the compressor is broken, a good £200-£300 part, with a broken compressor I can’t perform a leak test so there’s a good chance that I will have to replace even more parts for the AC. If you’re not handy with tools then it will cost you the labour too.
If you’re happy to buy the car I would personally argue that at least an oil service should be included with the sale of the car, I did that however the garage I bought from were liars.
I would be a bit scared without any servicing documentation. It is really up to you as what kind of owner you are! Chances are that if you’re a careful owner who is concerned enough to ask this on a forum, you may be better off saving your money for a really nice one.
Welcome to the forum and happy shopping!