Doreen,
You can rent a car one way. We did this and paid around 65.00 for a premium size car. The car rental place took us to the ship in a van when we checked the car in. When we got off the ship, the car rental place picked us up and took us to their location to get our car. It was very easy. We have a family of 5 and did not want to pay Disney's price for their bus, the rental was a great way to go. The Port is a straight shot from the Orlando Airport. It probably took us around 45-50 minutes to drive.