Figure out what vehicles will suit her needs.
Go to those dealerships.
Wander around the used car sections.
Look for the vehicle that she is interested in buying along w evidence that it has been sitting there a while-ie spider webs, dust etc....
offer the used car sales manager a lowball price.
Do not be surprised and be prepared to pay for it when he accepts your offer.
I also like to find for the salesman that looks like if he doesn’t sell a car soon he’ll be fired.