We spent $640 each, PHL-SXM, on American ( originally booked on USAir ), for 5 days, leaving 1-1-16.

Then, when we got cabin fever last weekend, after being stuck inside during the blizzard, we booked anther trip, to Guadeloupe, leaving out of BWI on 3-29-16 : $188 per person on Norwegian Air. Very easy to get from Philadelphia to BWI on Amtrak - one hour and 20 Minutes.

Car rental on Guadeloupe is a bit higher than SXM, but hotel is less expensive. The $188 R/T BWI-PTP on Norwegian is the lowest fare to the Caribbean that I have seen in decades. Good luck !