While this was probably true 30 years ago, today this is painfully wrong. If you browse the Caribbean forums you'll see that graduating from a Caribbean school does not guarentee you a residency and most graduates don't match. In fact graduating in the top half of your class with an above average USMLE score does not guarentee you a residency. There are now so many US medical students competing over the limited number of residency slots in this country that Caribbean grads need to have the kind of numbers that would get a US medical student a Derm residency (250+ USMLE, Honored the majority of their rotations) just to get into a single, malignant, backwoods family practice program so that they can see clinic for the rest of their lives. Surgery and Internal medicine residents from the Caribbean, though previously common, are rapidly becoming a thing of the past. And it will get WAY worse by the time you graduate.
That is, of course, if you graduate. Keep in mind that most Caribbean schools take more students than they have seats in the lecture halls. They're looking to take your money and run, and they don't care if the majority of you don't actually finish (let alone match). Compare this to a US medical school, which has countless mechanisms to make sure you don't fail out, no matter what. My class has lost 5 people out of 180 in three years. Caribbean schools lose more than half their class by the end of the first year. So to summarize you need to be in the small percentage of you class that graduates, and the be in the small percentage of the graduates that gets a residency, so that you can do work an NP would turn his/her nose up at while paying down 300K in debt.
So, like others have said before, don't do it. Either go to a US school or find a new career. You think an SMP is a gamble? An SMP is a gamble with $50,000 and a year of your life. If it doesn't work out you'll spend half a decade paying back the loans and that sucks but if you want medical school badly enough you need to consider taking your shot. The Caribbean, on the other hand, is a gamble with 4 years of your life and $300K. Simply put, if it doesn't work out you have ruined your life as completely and irrevocably as if you murdered someone. You'll never own a home, you'll never have any significant wages. You can't even go bankrupt. You will live with your parents until they die, at which point you will in all probability be homeless until you die. It's a bigger gamble.
And, BTW it's a gamble with much worse odds. I went thorough an SMP program, the odds of successfully matriculating at medical school for my class was 95%. Many respectable programs boast at least a 70% success rate. Caribbean school success rate? Maybe 10%. Maybe. It's a BAD gamble. Barely better than scratch off lotto tickets. If you can do well on the MCAT the SMP is a better plan. If you can't then finding another career is a better plan.
Now this is leaving aside the issue of what makes you think you are going to survive in medical school with a 3.0 GPA. That's another bit of serious introspection you need to do. But first things first: stop looking at the Caribbean. As many have said, finding a different career is a much better option than mortgaging your life to those government backed scam artists.