Airport Parking Reservations (dot com) offers options for as little as ~$5-7 per day at places like the Embassy Suites Hotel close by.
We didn't use it (had other people with us who didn't trust anything other than what they were familiar with), but I've heard lots of successful reports from using their services.
Also remember that the Port of Miami (there may be others, but this is the only one in Florida I know about) offers free parking for those with a handicap sticker or placard.
Other Florida ports offer free parking to anyone that has a handicap sticker AND a scooter or mobile device on the back of their vehicle.
COMPLETES THE FLEET
If it is Carnival and it floats....we have sailed it!
Hubby ... DIAMOND (every ship except the Carnivale)
Me ... DIAMOND (every ship starting with the Tropicale)
20 year old son ... DIAMOND (every ship starting with the Tropicale...he is the only DOUBLE Milestone under the age of 21)
24 year old son ... DIAMOND
United Airport Parking! Guaranteed Discount Parking and Free Shuttle Service this site has a place that is one mile from the port, a large parking garage, they have a shuttle service to and from the port, we have used and were very pleased. I do not know if the Embassy Suites Hotel has this service. I know that we parked at one of the hotels near the airport that had parking for the cruise port but they did not have a shuttle so we had to get a taxi both wayss and with the cost of that it was almost as much as parking at the port.
Star Princess 2005, Sun Princess 2005
Caribbean Princess 2006, MSC Lirica 2006 , NCL Pearl 2007, Majesty of the Seas 2008, Carnival Destiny 2008, MSC Lirica 2009, Carnival Valor 2009,Carnival Legend 2010, Carnival Liberty 2010,Carnival Fantsay 2011,Carnival Valor Feb 2012, MSC Poesia Dec 2012, MSC Poesia April 2013