@ 500 above offers a lot of good advice, there.
I know of one PPL who had a nominal share in an AERONCA (1950's fabric covered, swing the prop to start AKA "Armstrong" starting
a very cheap PPL by comparison with "spam-can" rental....BUT
AFAIK, due to all the regulatory changes, you won't be allowed to do an EASA PPL on a Permit aircraft (which I think is classified as "Annex 2" ....in plain english, it's a UK only , unless permission is sought from another country, to use it in their airspace.)...also, though a 2-seater and enormous fun, it was as slow as hell and guzzled AVGAS which is far more expensive than pump petrol, AKA MOGAS.
Permit aircraft, you can maintain yourself...a major cost-consideration other than Hangarage and insurance...not much use if you're not a spannerman.
A look on "Flyer" forum could be of benefit, several of the regulars here, also contribute over there!
I'm sure someone will be along to correct me shortly!...what I DO know ,is there is a directive from Cessna, to do a lot of inspection and replacement work on their ancient Spamcans (150/152/172 are the majority of cessna flying-school trainers) this means a lot will be , as you surmised, "beyond economic repair" SO BEWARE CHEAP CESSNA DEALS where the SID's have not been complied with.!!!!
If your son is going to fly and hours-build intensively, then ownership *could* make sense, but he'd need to do around 100 hours a year to make it worthwhile.
Why does everyone assume he
needs a car to get to the nearest "proper" airfield?....motorbike/scooter would teach him more roadcraft than all the "learn to pass your test" driving schools combined.....a compromise would be the odd BMW fully-faired "scooter "- effectively a 2-wheel microcar with no sides!
Alternatively, there's stuff such as the AIXAM and Ligier which is a tiny car legally a quadricycle....slow, but enclosed and ultra cheap on tax / insurance and fuel...drive them on a motorcycle license.
Browse this forum and you'll soon pick up the jargon and get a feel for the nature of Aviation....see the LAA website for information about Permit aircraft and their relevance to EASA (which, it appears, is now the universal diktat of all things Aviation in Europe)
To just fly, Microlights *can* be ,at first viewing, *normal* light aircraft, but a reduction in engine-size and / or increase in wing-area makes for the reclassification. British Microlight Association website
My personal take on it , - the less regulated by EASA the more restrictive the usage and the more limited the class-specific license.
IF you browse the forums, you'll pick up an essential piece of advice
"NEVER PAY A LARGE SUM UP FRONT TO A TRAINING-ORGANISATION.
They go bust with monotonous regularity, taking all the prepaid dosh with them.
Sorry, long post, but so much ground to cover!