I have never done this, but I have discussed it with Tiffany Towncar drivers when they took me from the airport to my hotel. They said that they will do it. I did not ask about prices. I suggest giving them a call.
I took a cab from Beach Club to Sea World. The cost to get there was $23.65 (plus tip). I didn't write down the cost for my return. I liked the flexibility of coming and going when I wanted, without having to plan it in advance with a towncar company.