My sister has had a business along the eastern seaboard for about 20 years. In the spring she flies to Florida, then rents a car and drives north servicing her accounts along the way. In the fall, she rents the car in Maine and drives south servicing her accounts along the way. She has done this for years, watching for the "one way" promotions and booking her rental car for as little as $85 (the rate I remember from 3 or 4 years ago) including use of it during her Florida vacation. Some years quite a bit higher than that, but always a good bargain given that she does have to drive one way - and doesn't use her own vehicle.