I used to tell wannabe owners that "There is no such thing as a cheap old airplane." This was based on experience acquired in fixing the numerous deficiencies in neglected aircraft. I was dismayed, especially, by the costs to the new owner at the first annual. There were those that spent as much on that annual as they paid for the airplane, and the thing still needed paint, upholstery, a new engine, panel upgrades and so on. It was still an ugly old airplane, just airworthy for the first time in a long time.
Too many people find such "bargains" and get stung. Remember that many such aircraft have been owned by people who were increasingly unable to afford them, so maintenance got shorted. Defects deferred or ignored. ADs missed or far past recurrency.
These aren't old cars that can be restored by their owners. Most owners don't have those skills and they don't know the mass of regulations around aircraft repairs and maintenance and modifications. They're pretty much stuck with paying some shop to fix it, and mechanics aren't doing this for fun. It's their living.
At the flight school we bought low-time, older 172M's as trainers. We flew them home, and promptly tore them apart. Overhauled engine and engine mount. Old, cracked and corroded exhaust replaced. New engine hoses. New mags, new or O/H alternator. Fuel tanks out for inspection and repair and replacement of the rubber "bumpers" that supported them, and new vent tube connection hoses. Sometimes even the fuel selector came out for cleaning and new seals. New upholstery and carpet to replace the crumbling 1970s stuff. New seat belts and should harnesses. Some new instruments, new ELT usually, new radios that worked right. Repairs to the flaps and their rollers. New control cables where necessary. New engine controls no matter what. They get old, too, even when the airplane just sits.
This way, that airplane was dispatchable 99.9% of the time. There were very few failures that grounded a flight. Losing revenue flights is much more expensive than doing all the right stuff up front.
