Ft Myers and Port St Lucie aren't nearly as expensive as Dade, Broward, and PB counties. Ft Myers is gulfside, Port St. Lucie is on the Atlantic. The latter is a good area because of its proximity to Orlando and Miami. The former seems like a safe bet because large businesses are opening shop there.
If I were a speculator, and this is merely a guess, I'd wait two years to see whath appens in Port St. Lucie. There's a glut of newly built homes in the area and prices have started to level off. I'm guessing there will be a drop in price soon.
Also keep in mind that Port St. Lucie sucks aside from the beach. I would never want to live there.