Forget Avis, it’s ridiculously overpriced.
Ask a relative to take you to a rental shop one day and you’ll find half a dozens other shops in the area. They’re all located next to each other. I cant tell you specifics because I’m not from Lahore, but trust me… they wont be hard to find. A directory might help.
1500 PKR sounds reasonable. You’ll manage to snag something even cheaper if you commit to 3 weeks. I also noticed, oddly enough, that cars from these small outfits cost less with drivers than without drivers. It must be a liability issue.