We used a one-way car rental for several of our legs in April, i.e. WDW to port, port to MCO, home airport to house. It was always cheaper than the limos, taxis, etc. except for MCO to WDW when we used Tiffany which by the way was only 15 mintues late and the comped the ride for us.
The Avis drop at port is at the Radisson, very close and convenient. We paid about $50-ish for large 4 door. Also gives you flexibility to explore, eat, shop, etc. depending on your flight times.