You have lots of great options! Don't give up on the boat charter, however. It sounds like you've seen the high-end charters with fancy food. It also can be done more simply.

Check out the sponsors here. Captains Compass can be budget friendly, and he could probably arrange crew. You could provision your own food. Another option is to charter out of St. Thomas, which can cut down on transportation and food costs.

At this point, my biggest concern would be knowing that any deposit is not at risk.