Actually we booked an excursion through Carnival and I think it was $89.99 per person for a two hour trip that includes the beach, a trip to " Fish Fry", and a refreshment break. It's at the bottom of the excursion page.
I would also recommend a self guided walk to the Pirates Museum and Senor Frogs. Why pay the extra money for an excursion there when they are a short walk from the ship through the Straw Market. That place is so crowded and the aisle are so narrow that it is claustophobic. The Senor Frogs is one of the best I have ever been to.