It is worthwhile to check neighboring states to see if they have a free transponder option that will work in the state you are visiting. I see that North Carolina has a free transponder option that works in Florida, but the North Carolina website does not give any guidance to using the their system in a rental car so that might be a catch. In my case, I got an EZ-Pass transponder for the Northeast USA area and chose a state toll system that didn't charge for a transponder rather than the state I was actually visiting.
Compatibility with BOTH Sunpass (Florida) and EZ pass (northeast + IL)
As long as there is activity in the past month, there is no monthly service fee
You can add and remove a license plate online.
Customer service for NC is horrible
Customer service for NC is non-existent if you have an issue
Likes: Neil Maley