The Caribbean Compass is one. I'd start there and most of the marinas with storage in these areas have a list of their boats for sale.
As there are definite cruising seasons; Atlantic crossings, US/Canada to Caribbean trips, voyages to Hawaii from Ca, etc, you can keep an eye out for the new boats as they come up for sale. They are generally overpriced at first but come down quickly as the need for that equity increases. I know it sounds cold hearted, but it is just a business deal after all.