The AZ drive out in the spring, and more limited drive in during the fall, typically occur each year. The prices tend to be at least $19/day for a compact. Returns are sometimes allowed as far as OH.
Gas probably wasn't why the FL driveout increased prices. That happened around the time Hertz bought Dollar Thrifty, whose one way specials were previously always $1/day for a midsize. Hertz back then offered subcompacts at $5/day. The special rose to $19/day for economy through fullsize for a few years, led by Avis, then dropped steadily to $9 during the spring. Now it's usually offered at $9 in the beginning.