I'd do with Mears, too. When I lived in Orlando, I always used them when I needed airport transportation.
Mears has a taxi fare estimator. It's not that user friendly because you need to know the address (including zip code) to get an estimate for a Disney Resort. Although technically none of the Resorts are in Orlando, you can use that in the city field.
http://www.mearstransportation.com/taxi-services/taxi-fare-estimator/
Some examples of fare from the Orlando International Airport:
- Disney's Wilderness Lodge (901 Timberline Dr, Orlando, FL, 32830): $63
- Disney's Animal Kingdom Lodge (2901 Osceola Parkway Blvd, Orlando, FL, 32830): $62.50
- Disney's Pop Century Resort (1050 Century Dr, Orlando, FL, 32830): $56.95
- Disney's Port Orleans Resort - Riverside (1251 Riverside Dr, Orlando, FL, 32830): $54.18