You won't need an excursion for that. Just take an approved cab to the beach and then when ready to leave, take a cab to Margaritaville. Then a cab back to terminal.
If you are really adventurous, want to see the real Jamaica, would like to shop at a non threatening craft fair, eat at a real local Jerk stand, and still enjoy a great beach and Margaritaville, contact Carolyn Barrett at
www.barrettadventures.com and set up the "Tom Sodemann" excursion. Then go on this web site and invite other people to join you in order to fill her 15 passenger van with 12 people (comfortably). The total cost per person will be about $20-$25 dollars. You might even make some new friends!
We did!
Your way, the taxi's will cost at least $60 for the 3 legs.
Good Luck