there are flights between Orlando and Miami nearly hourly ... {it is over 200 miles}
DCL does have shuttle available from MIA to Port of Miami .. or a taxi is $27 flat rate (per car, not per person) ... or UBER
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there is a 'luxury' bus
travel time is roughly 5 hours, Orlando (near airport) to Port of Miami
cost varies but typically in the $90 to $100 US range (some times cost less, some discounts for booking multiple seats)
http://www.redcoachusa.com/
expect some extra costs too as the 'terminal' at the Orlando Airport is not in the airport so there will be a taxi fare ....
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MEGABUS is a 'not luxury bus' that can take you city to city for $26 per person .... but add costs to get to/from the terminals by taxi or UBER
https://us.megabus.com/
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flying to Ft Lauderdale or even West Palm Beach cuts your transfer problem down to size. A car from Ft L costs WAY less than from Orlando, and from either place you can take the train and get within a short taxi/uber ride from the port.