There are several ways, Allegiant Airlines (God bless em), (soon to be) Jet America, and to find those terminals (if you are in the hinterlands) in South West.
Find a way to an Allegiant Air, Jet America, or South West Airlines (they were the first ones to "get it") terminal. NO I am NOT a sponsor or gaining ANYTHING from them. BUT they and Jet America will bring you to Florida for MUCH less than you can drive it (and non-stop).
THEY have IT figured out. Trust them and don't check your bags. Carry on and don't do assigned seating.
For a cheap rental car, start with Priceline and throw them nothing.
I have got great rides for under $18/day, serious. I have stayed on Collins Ave at the SHELLEY Hotel, I believe on SOUTH BEACH, MIAMI, for $25/night. I HAVE the receipt in hand.
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