I go both ways with cropping. Basically for me, it depends on A)whether or not I will be showing the dog and B) what those ears would be shaped like if left natural.
I prefer natural as long as the ears grow in a sane manner, I like rose ears, half prick, and half rose. I would crop them if they hung like labs ears, or were to big. I own ADBA dogs currently, and allthough cropping is not required for a show pit, they tend to win over natural ears. I would rather have nice looking natural ears than nice looking cropped ears. Cropped ears are a double edged sword-- in the show ring your dog would look more alert, more powerfull. On the street your dog would most likely be perceived as dangerous, and scary.
I live in Florida too, and all the vets in my area do it right at 16 weeks. They won't do it sooner for fear of negative effects of anesthetics, and they won't do it later for fear of the cartiulege not setting right. You can expect to pay anywhere from $250-$800 for an ear crop. In this case more expense does not mean better quality, shop around, make sur they have experience cropping Pit Bull ears, and bring several pictures of the type of crop you want.