25+ years ago my parents bought an ex-rental car (this after one of my brothers managed to wreck the family station wagon). As I recall, it was not particularly cheap, certainly not a lot cheaper than a well-cared-for car off a dealer's lot. The car lasted for a couple of years - at least till said brother was off at college - and was replaced with a newer car.

I think I'd look elsewhere given how some drivers treat rentals (and the general mechanical condition of Hertz rentals I've recently had)... and given how I see the car-jockeys at the rental lots handle cars.