We chartered a boat in Cozumel. It was $400, and was just one of the ones along the walkway. Bad bad bad idea. The person who we chartered with spoke great English. Guys on board didn't speak any. There were 4 poles on board, 1 for each person in our family. No bathroom, etc. And leaving at about 1pm meant that no fish were biting. We couldn't explain to the guys that we wanted to try catching anything, they just assumed we wanted to catch a big fish, so we couldn't get them to move out of the deepest water. We kept trying to explain that with kids, they don't care how big it is, they just want to catch a fish.
Finally, I got violently sea sick, and we managed to convince them to just take us back in. We were probably out about 2 hours, and paid for 4.
On the other hand, my DH did the CC excursion and had an absolute blast. He caught lots of fish, including a very big shark. That's the excursion we're taking in the future!