The Florida Trail: The Official Hiking Guide
I checked Sandra's site and this is now out of print and she says she is working on an updated one. If you can find one it would be enough to do the trail. Like I said I'm a map freak, but I can understand $100 worth might be a bit much unless you are sure you are going to hike the entire trail.
Also, you will need FTA membership to hike through the Indian Reservation and some of the private and military lands.