I don't know what part of Florida you are in, but I have a small cottage in Siesta Key that's pretty much available until December. If you are interested, email me at firstname.lastname@example.org Otherwise, here is a good Florida rental site for you to check out for other vacation property rentals: http://www.weneedavacation.com
I have found that most resort areas will have homes for rent cheaper than the nearby hotels. I can't comment on other areas of FL, though, so which way you go, will depend on where you need to rent. Good luck!