The dealer should tell you how much they make you deposit for the core fee, and that would only be for DIY. If they install it, there's no reason for a core fee because they already have the old battery in their possession. I know it's a bit of a long trip from Gainesville, but Home - Tampa Hybrids Inc. should give you a WAY better price than a Toyota dealer on a new battery.
Brand new is about USD1,600. It doesn't include installation. And you could sell the old battery is about USD300 when you go somewhere to have it replaced.