Car Hire/Sat-Nav Options in Florida

[~ vortex ~]

Can anyone help me pls..? Is it cheaper to pay for a GPS system as an extra included item when hiring a car in Florida or cheaper to download a map for my Tom Tom and take it with me? Ive checked out some car hire comparison sites and they say you have to pay for the systems locally and dosn't give a price. It costs approx �25 for a map download. I don't want to download a map if I can help it because It might be a while before I go to the USA again so it might be an expensive one off. If anyone has had a GPS as an extra item, can you tell me how much I would expect to pay? approx? Many thanks in advance