Yes, the sea taxi operations are run by kiting schools, more at:
http://fksa.org/showthread.php?t=4866
http://fksa.org/showthread.php?t=1263
http://fksa.org/showthread.php?t=3519
http://www.miamikiteboarding.com/
Even if you have a boat, it would be best to go out with the Pros initially to learn about boat launch, the Flats, channels, tidal ranges, riding areas, things to avoid, etc..