Acquaintance is turning in a leased car that I want

And acquaintance is turning in a leased Toyota Prius, that is the right year, mileage, color, everything that I have been looking for, and unable to find. We are both in the same county, and the same state of Georgia, USA

I asked him to find out what the buyout is rather than just turning it in, and I would pay him 15% over that. Is there a way I can do this so it’s the least painful for him? I assume he doesn’t have to register it, but I imagine he has o buy it and then there’s sales tax and I would buy it +15% plus sales tax. Has anyone done this before, or have any suggestions? Help and guidance is much as appreciated.