Perhaps its not relevant to compare prices in the US to prices in JA, hey, I didn't like the cost of things in England compared to the US when I went there... its based on their internal economy. The US has enormous land and people resources, thus many things cost less in the US, as profits are generated by selling many units of a thing.

As a future long-termer/resident, just compare prices within Jamaica, and you can do all right. It pays to look around and shop around, even in Negril. Prices vary from store to store and some will negotiate. Shopping can be more personal/in-person here.