If you drive to Maine it will save you money. They give a decent discount for using ez pass.

As long as you get one from Rhode Island- it's effectively free to own minus the account minimum requirement. Some States (NY/NJ/Maryland) charge a monthly maintenance fee if you don't meet some usage requirement, RI doesn't as long your statement is delivered by email. And as a RI resident, with RI plates it'll get you over the bridge a lot cheaper than the pay by mail option (once you provide the support documentation).