Here is my experience renting for the first time in Cancun. I saw lots of incredible rates like $1 per day on expedia etc, but figured it all came with hidden expensive insurance. I booked a prepaid rental with Sixt, which was about $30 per day, and I also prepaid $10 per day for SLI. At pickup, I expected a hard sale on extra insurance, but it was a mild soft sale, which I declined. However, they said they required a deposit of about $2,000 on the credit card (in pesos, do not remember the exact amount) because I did not buy their CDW. My credit card approved the deposit, so I was able to rent fine. They even gave me an upgrade as Sixt Platinum. The car was pretty beat up though, with a LOT of scratches and dents. No attempt to "find" and charge for any extra damage on the return, so that was another thing I worried about but turned out fine. All in all, OK experience.