Just went on a cruise a couple weeks ago with stops at St. Maarten, Barbados and Martinique. I did not see anything in Martinique, but it was our last stop and we woke up late and did not have much time there. We hit Barbados on a Sunday so all the downtown stores were closed; all we saw were the shops at the Terminal, which did have two stores with some upper swiss brands, but nothing major. St. Maarten had damn near everything under the sun. Best place for selection hands down. Price? IMHO nothing special. Most brands were offered at 10-20% off retail, which was not much better than prices I could get locally (for the brands I can get locally). Seiko and Citizen were offered at deeper discounts (50-60%). The reps on St. Maarten that I saw were of Canal St. quality at twice the price; poor, cheap knock-offs.
So, in short I don't know that this post will be much help. But there you have it.