Unfortunately, Orlando is one of these locations where avoiding tolls is more hassle than it's worth. The system has been deliberately designed to make visitors pay for the infrastructure instead of taxing the residents. All major roads leading to/from attractions and the airport are toll roads, and avoiding the tolls requires travel on congested secondary roads with lots of lights. I gave up on trying to avoid tolls in the area at some point because the time gained more than made up for the price of the tolls.
In places like Orlando or NYC where tolls are a fact of life if one wants to get around, I usually rent from Dollar who have an all-inclusive option for around $50 a week (includes fees and all tolls) which is absolutely hassle-free and cheaper than Avis where tolls are added on top of the fees at the highest rates.