Negotiate in the port. We had 12 people and did it for $15 per person. You do pay $10 per person extra for the turtle farm and $2 for 7 mile beach. Still a good value.
Turtle Farm Rating:
Love the turtle farm. Fun to pet and hold the turtles. They now have a little wading tank that you can get into up to your knees and play with the baby turtles.
Not the best port. Make sure to go outside the security zone of the port and visit the Jade Museum. Joseph and his dad speak good English. They also have a very impressive gift shop. We bought necklaces for the kids at $20 each. Tell Joseph that the New Mexico dentist sent you. He and I have been conversing back and forth via e-mail. He's super cool and knowledgeable about the area and history. A must see in Costa Maya.
Had a good time. They need to allow more time on the beach- only had 60 minutes. The snorkeling gear is included and the line dancing on deck on the way back into port was fun.
More 
