The Sunpass site is pretty good and has a list of retailers where you can pick one up as well as a toll calculator. Without the exact route, its just a guess but I picked a starting point in Ft Lauderdale and an ending one in orlando and the total cost was under $15. I don't remember if there are other toll roads on the route but, you can link a bank account to the sunpass just like ezpass so it will reload itself if it reaches the low balance that you select.