I know someone who was having problems with a used German car (top of the line brand) with compressor leaks or or evaporator. The part and install were something like $1,500.
I suggested one of those leak sealing kits. There are a few of them out there. Some are better than others.
Anyway - they had the mechanic put the stuff in and it has been fine for 6 + months.
Could work. There are ways to detect leaks (soap bubbles or electronic)and many can be fixed without evacuating. Those R22 systems should last 25 years. Some of these guys are “hungry” alright. They are incompetent or liars in many cases.
I always said if doctors are like HVAC service guys, how do you know if you have one of the three-in-ten who know what the hell they are doing?