Is it really only $15 US dollars to rent a car in Cozumel?
that's about right. But they will put about a $1500 hold on your credit card
I used to rent in Panama. The deal was the car was cheap but insurance was expensive and mandatory. When you returned the car they always found a new dent. You could give the guy ckecking you in a $5 and he would let it go.
they will charge you by other way
Yes. All you need to do if find out who is doing so.
Probably not. The insurance cost for a day would be at least half that
I looked on Expedia and didn't see anything for $15, but they are pretty cheap. I would definitely go with a legitimate rental agency.