And another idea: we had an exchange to Grand Cayman this past January. When I first looked at flights, round trips were on the high side. There was a relative I had contemplated visiting in FL, so I checked flights for Tampa - Grand Cayman - NC ... sorta like an open-jaw, except different departure and arrival cities. Prices were hundreds of $$ lower than round trip NC-Grand Cayman at the time. Then I found a back-to-back exchange to FL, and a cheap 1-way flight on SW from NC-FL, with total flight costs lower than the round trip. Later on the round trip fares came down some, but we still came out better doing it this way, and got to spend a week in FL too.
So ... you might check out that kind of itinerary, especially if Southwest flies from your city - see if it could save you $. Lowest fare was out of Miami, but not much more from Tampa (which we used) or Orlando. It was either AA or Delta, I'd have to check.