Not sure if this is still a possibility but some of the timeshare presentations (in the past) used to offer a St. Barts trip as one of the "prizes" for putting up with the presentation. If they still do, for an hour or so of your time you might be able to get a trip this way.
We went years ago and did one of the ferries. Not bad but it makes for a long day. Glad we did it but no desire to do it again.
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