I looked into just about every options going from MCO to the port....taxi, private car, disney transportation and renting a car. For us, a family of 4, it was cheaper to rent a car for the day and drop it off at the port. There is a shuttle that runs every 20 minutes from the car rental office to the ship. I'm renting a car at port and dropping it at MCO on the return as well. It's $70 round trip per person on
DCL transportation ($280 for my family) vs. roughly $114 I'm paying for 2 rentals. Plus we have a little freedom to go visit either Disney Springs or Kennedy space center for a little while before our afternoon return flight.