Generally within the state of Florida, there are no drop-off charges. You should be able to get the same or similar rates as if you dropped in the same place.
However, I have heard that sometimes if you're using a discount coupon, the terms of some of the coupons may state it does not apply to "one-way" rentals. I'd still try to apply it anyway and see if you get the discount, since a Florida to different Florida rental may not be considered one-way.