Mears Shuttle is $20 pp round trip.
Tiffany Town Car (for example, other car service providers would be comparable):
one to four persons = town car = $80 round trip
up to ten persons = van = $90 round trip
Advantages to a car service would be (a) personalized service: you arrange specific pickup and return times, and the service caters to you (shuttle has you call two hours before you want to head back to your resort); and (b) you don't share the ride with anyone else or stop at multiple locations in either direction.