We are going to be visiting the Keys in November of this year and I am having a hard time figuring out the whole toll fee situation in Florida. If I am understanding this correctly, we have to buy "something" that we attach to the inside of our front windshield below the rearview mirror that has something to do with the tolls. Do I buy this from the car rental agency, (we are using Alamo) or do I purchase it from any CVS or local store. The locals do it so why can't we is my reasoning. I have heard that the car rental agencies are scamming the tourist by charging exorbitant fees for them and so I need help!! Can anyone clear this up for me?