Living in the Caribbean could be more expensive overall. Some things are cheaper but most are more expensive. The cost of living will depend on your lifestyle and what you're willing to sacrifice to enjoy the luxury of the Caribbean. Location will also be another major thing that determines cost of living as you'll read in the next few paragraphs.
Groceries & Eating Out
Food prices are generally higher due to the fact that many things need importing. Fruits and vegetables are generally cheaper because there is some agriculture on the islands. Everything else, including water, milk, and eggs are generally higher in price than in the states.
Dining out applies the same way. Eating out at a restaurant, café, bar, or beach shack will cost you more than eating groceries. If you are trying to stretch your income than eating groceries at home will save you money.
Whether you are planning on buying a house or renting an apartment, the prices are definitely higher in the Caribbean. Renting an apartment in the center of the city will cost you more than getting one outside of town. Houses are usually double to triple the cost than they are elsewhere. Buying an oceanfront house can easily cost you a million dollars if you pick a big house with many features. If you are on a budget, it's advised to pick a place outside the city and one that's not oceanfront. Getting a house that is a short walk to the beach but not oceanfront will save you a significant amount of money. Getting an oceanfront condo is usually another way to save money but many buyers hate paying HOA fees because it's never paid off. It's like a never endying mortgage.
Just like most things, utilities are generally higher on the Caribbean. Electricity can cost you up to double on the islands. Phone calls can get expensive because long distance charges could be high, especially when charged by the minute. Internet will be higher also. The good thing is that there is no need for oil and gas for heating. This will save you hundreds or even thousands of dollars per year. Since the Caribbean is warm all year-long you will actually save more money by living in paradise than you would living in the north, whether it be the northern part of the United States or Canada.
Healthcare really isn't that expensive in the Caribbean even though medical treatment could be hard to come by. Some of the islands only have small hospitals, clinics, or doctors offices. If major medical treatment is necessary then you'll have to get flown in to Miami or one of the bigger islands, depending on where you are.
Transportation in general could be cheap or expensive depending on your lifestyle and where you decide to live. Will you be living on a small island, near the beach, convenient to everything. If so then you'll be able to walk on foot or ride a bike into town and save money on a car. If you are on a big island then you'll need a way to get around such as a car, bus, or taxi. The price of cars are around the same as they are in other countries. Here's the scary part; the price of gas is very high! Gas costs around $1.30-$2/L depending on the island. That's around $5-8 per gallon! The good thing is that the farthest you'll be driving is around 100 miles (162 km) on the biggest island. Most islands are only 20 miles (32 km) or less to the other side so a tank of gas will go farther. Taking the taxi can get expensive if used daily but if you usually walk/bike everywhere than a taxi will be the better way to go. Buses are also a cheap way to travel.
Location, as seen above, is probably the biggest thing that changes the cost of living in the Caribbean. Bigger islands have more convenience and cheaper costs on products and smaller islands are easier to get around. If you are on a tight budget then consider taking ferries to other islands or a plane to Miami to buy products at a lower cost. You may have to change your lifestyle to afford the luxury life that the Caribbean has to offer but it will be worth it.