(Not so) random thoughts ...
What we don't know:
- Over what time period did the A/C digress from working well to not at all (see below*)?
- How long has it been that it hasn't worked (sitting static)?
- Has there been any prior work on the A/C?
- Who are these "people" that want to sell you a compressor?
A reputable shop won't sell you parts or services not needed; hunt for one.
2001 compressor has died? If he plans on keeping it for a few years, it may be worth fixing it (correctly). Maybe he's gotten his moneys worth from the original.
If it's true that the compressor won't turn, then maybe it's kaput; maybe it has seized and cannot be freed. If it's been sitting static for very long, it's toast. Atmospheric humidity has probably rusted the innards or caused the remaining oil to degrade, and the only way to get rid of that is by evacuating the system for which you'll need a vacuum pump and a set of manifold gauges.
A friend who used to be a mechanic and then a service manager told me to amortize non-maintenance repair costs over the time of ownership. His thought is that if you can drive a vehicle for 200 to $500 a year, that's not bad.
*There are cases when I'd recommend a simple "top-off", but those are few. One would be if the symptom is cooled air out of the duct was around 60 to 70'F and had been this way for a six-month period or longer. The system would probably be low on Freon and still have sufficient oil. I'd try a top-off, but only once of it didn't work for at least a year. And I'd not use any leak stop because that may accelerate the wear of seals at moving parts, and that's counterproductive. I might use a UV leak detector, though.