Last March we paid $40 - $45 for a 4-hr cart rental, it was the last cart available except for another outfit that wanted $90 for 4 hrs (supply & demand). Normally we would pay that price for a full-day rental. You’d need at least 3 carts so taxis would make more sense for your group.

Carts are fun to drive around for 2 - 4 ppl for sightseeing, and you may want to do that one day...

The IM forum on TA is pretty active and you will find more current feedback there. The Top Questions section is also helpful...
https://www.tripadvisor.com/ShowForum-g150810-i360-Isla_Mujeres_Yucatan_Peninsula.html

Last edited by crmoores; 12/23/2018 10:39 AM. Reason: Added TA link
"Travel changes you. As you move through this life and this world you change things slightly, you leave marks behind, however small. And in return, life — and travel — leaves marks on you.”
-Anthony Bourdain