I can't speak specifically about the rest of the Caribbean, but it's virtually impossible to find a paying DM job in the Caymans.
When you get your Instructor, though, the world is your oyster - travel anywhere you like and it's almost guaranteed you'll find a place that's hiring.
As for how much you'll make, well... enough to get by, but you're not gonna get rich. It's not really a career so much as supporting a habit, remember! And, unfortunately, DM jobs, when they are paying, tend to pay even less than teaching jobs.
One option to consider is working for an all-inclusive resort - a Club Med, say, or something similar. Usually they'll provide you with room and board in addition to salary, and it's a better deal than just salary on its own. A friend of mine works for an all-inclusive in the Dominican Republic, and gets room and board plus $700 a month. More money than I'll be making, that's for sure...
Check your cert agency's website for job listings, though, if you aren't looking to get your Instructor anytime soon. There are fewer listings for DMs than Instructors, but they are there. I'm scanning PADI's at the moment, and there are a couple listings for Cypress and the Red Sea. Good luck!