I'm a nontrad too, and I certainly worry a lot about my chances of getting into med school. (Just applied this cycle.) But, based on some horror stories I've read on SDN, it seems way too risky to go to the Caribbean for med school. Not only do Caribbean grads have to fight it out with US allo and DO students for residencies, their educations are significantly more expensive AND they can't get financial aid or government-subsidized loans. This can really backfire on you if any of your financial arrangements fall through, because you can't finish your education, but you still have to pay back the money you've already borrowed.
Just last week, I read on SDN about a student in this very situation. Here is the thread:
http://forums.studentdoctor.net/showthread.php?t=525293
This guy has finished 2 years at a Caribbean school and passed USMLE Step I, but his lender won't let him borrow any more money, so he can't afford to finish at that school. But because he's already borrowed a lot and the value of his house has declined in the real estate slump, he'll probably have trouble finding another lender. In other words, he's up a major creek without a paddle.
Stories like these have convinced me that the Caribbean is not a good option for most people. I know that people who go to the top Caribbean schools get a solid education, but even those relatively "elite" students have to fight for a place in the US residency system. And if you're unlucky enough to have academic or financial troubles at a Caribbean school, you're toast. No one in the US system is going to lift a finger to help you.