According to
Florida's Turnpike - The Less Stressway™ | Traveler Information | Paying Tolls the only place where you need Sunpass and are unable to use cash is in the Miami/Dade area which is south of Disney. You will still be able to pay cash along the way to Disney. I went to the airport in Orlando recently and there were toll booths to pay cash. If you need to go to Miami/Dade area via the turnpike you would need the Sunpass.