It depends on what type of snake we are talking about. Florida has banned some snakes that aren't on the federal ban so obviously you can't ship them into the state.
As a Florida resident I have purchased ball pythons from out of state breeders who I'm sure do not have a class 3 wildlife license in florida.(the required license to sell reptiles) I honestly don't know the exact laws regulating this as they are difficult to even find... and the few that I have are so vaguely worded that they could be interrupted in a few different ways.
Here is the site that I have found the most information on reptile related laws in Florida:
http://myfwc.com/license/captive-wildlife/