Just returned on 11/25 from Eastern Carribbean. Without a doubt the duty free store in the pier terminal in San Juan is the best and absolutely cheapest. We also visited St. Thomas, St. Maarten & Nassau, so say San Juan from experience. A bottle of Absolut Vodka as $9.50 and Bacardi was $6.50, Bailey's Irish Cream was $14.99!!
St Maarten had a 40 0z. bottle of tequila , the one thats a golden colour, square bottle "E'Special", for $12.95. But the terminal in San Juan is good too! I noticed most people bought their liquor in St Thomas, we did't because we are Canadian and so are not allowed to bring back that much. I'm told the St Thomas was the place to buy because it is US. duty free as opposed to another countries duty free, if that makes any sense. When we got back on board in St Thomas the line to register your liquor purchases were enormous, and they had trolleys of liquor that was going to be held till after the cruise.