Just got back from Cancun. We told them we had food and they checked us. Friends of ours told them the same and were not checked. Another couple had all their cooked food taken away. They checked all our food, and took away our cheese as it was in a zip lock bag rather than the original packaging, and told me Cheese needs the same stamp as Chicken, USDA Approved. They allowed us our Empire Chicken, Empire Hot Dogs, Meal Mart Turkey Breast (Costco), Bread, Cans of Tuna.
The Empire Chicken was the type that you microwave for 22 minutes and its done. It was pretty good although the BBQ version is better than the herbed version. We picked it up in shoprite in the fresh section for $10.99 for a 3lb chicken.
We went to Walmart and picked up groceries and fruits and veg. You can pretty much find all the basics that you might need. Items that we could not find were canned tuna, light mayo. Bread can be found but its not easy, and we brought our own.
There is a kosher butcher which appears to be a branch out of Mexico City called Shuky Kosher that also has a restaurant. I did not go, but I spoke to the butcher, several people who went, as well as the Chabad Rabbi. The butcher has all types of chicken and beef and prices appear reasonable. They told me rib eye steak worked out to be $9/10 a pound, and chorizo was around $6/7 a pound. If and when I go the next time, I plan to get all my meat and chicken there, as there appears to be no reason to schlep.
The challenge with the restaurant is the mashgiach, who is not always around, and may or may not be an issue for some. One gentlemen told me his wife went around to watch one of the locals cook their food, once they found out that the mashgiach had gone. Everyone indicated that the food was good and reasonable priced.
Only caveat is that he stays in business because I'm not sure of the economics given the size of the community. I'm thinking the owner comes in from Mexico City every so often to check on things and that is it.
Hope this helps anyone thinking of going.