I bought a SunPass transponder that suction cups to your windshield. I picked it up at a Publix but they also sell them at toll plaza rest stops. It is cheaper because they charge more when you pay cash at booths. A few in Orlando don’t have booths. I mainly got it because I have family I visit in Ft Lauderdale, then drive up in rental car to Orlando. Many tolls!
you would have paid extra because toll by plate is more, and depending on what the rental company is, they all have admin fees for tolls. It varies company to company. For instance Alamo charges admin fee only on the days you use it. BUT Budget charges admin fee for every day of your rental even if you only use it one day. Most people never look at what the rental company policy is for tolls. And the rental companies never tell you unless you ask. But because I frequently rent in Florida and there are a lot of tolls I googled it.
Some of these so called discount rental companies have the highest fees.
I found Alamo to be the best. But after they made portable transponders I bought one of those.