Wouldn't it be easier to take I-4 all the way to WDW? Then take Exit 67 and you're there. One year we went, we took I-4 all the way to Daytona Beach and back. I don't recall having to pay any tolls on I-4. Of course that was about 4 years ago and things could have changed since then.
When we drive on 417 from the airport, there are 2 tolls I know we pay. The first one I think was $1.50 and the 2nd one was around $1.75. After paying the 2nd toll, we take the International/Epcot exit and there are no more tolls to pay.