Generally, you can find some stuff cheaper, usually booze or cigarettes (sometimes), stuff that had a large tax burden in the states. Two instances come to mind. I picked up a 2 liter jug of Stoli on St John in the mid 90's for less than 6 bucks (at a little liquor store next to a grocery) and checking at the duty free in St Thomas when we left, they wanted $14. I got my booze to take home from Isla Mujeres in a little store for less than half what they asked at the duty free in Cancun. Never really found any good deals at Belize Int. It might be interesting to see what something like One Barrel costs on AC and bounce it against what the duty free is asking, just for a comparison.

Been there, done that, the washing machine ate the T-shirt