Depending on the number of people the $75 for the taxi may be the cheapest. We've used this shuttle company before. The price was not bad for 4 people but the price was higher to bring you back. Their VIP meet and greet is pretty good too. They meet you at the luggage carrousel instead of you going to the curb to find them.
http://www.floridalimo.com/
You can set up reservations on their web sight and get set pricing.