A few links that may help you:
http://www.hsmv.state.fl.us/dmv/faqmotor.html
http://www.miamidade.gov/taxcollector/auto_tag.asp
http://www.miamidade.gov/taxcollecto...ated_links.asp
This one is relative to Hillsborough County but kind of decent at explainig the fees. Dade Counties fees may differ.
http://www.hillstax.org/motor/mvfees.asp
The Tax collector should issue you a temp tag which will allow you to opeerate the vehicle on florida roads until your new florida tag arrives.
Is this a private sale or a dealer?
Sorry, Im working or Id give you more info.
Gordon