klcman is right, stores are all over town!
And... if you forget something you can always buy it at the airport too!
Don't forget to purchase bunches of Marie Sharps, Viper Rum (lol), and have some Belikin loaded up for you at the duty free shop to take home. OH... there is some GREAT anti itch stuff I would recommend called Itch-A-Way. I've never seen it in the states so I had a friend ship me some out. Now I see it has a hotmail address.
Have a great trip!