We got a taxi $26 for 7 of us to Paradise Beach for the day. Admission was $12 per person and chairs were $2 a piece. Lots of water toys to play with, beautiful water and not crowded with a ship excursion. Lunch/drinks were reasonable and overall we had a really fun day. There were only two ships in port the day we were in Cozumel. The taxi driver told us that the max they can hold is 14 ships and when they are all in port together it is >30,000 cruise passengers on the island. I was glad it wasn't that busy.
We bought tequila in the port shops and it was cheaper than the duty free on the ship.