Boat insurance seems to be affected by Hull value, cruising grounds, and season. I bet there are others. My insurance is $379 for a year through West Marine. My hull is at $25k and $300k liability. I am limited to 15 or 25 miles offshore and not going West of Cape Flattery or North of Cape Scott. That basically limits me to the area I would normally sail in anyways so no big deal.
For the Carribean I imagine it jumps up dramatically in the Hurricane season and where you will be based in that season. It may go up again if you go south of some certain point.
I have a neighbor with a larger more expensive boat that pays less than me, but he didn''t know what his liability limit was or what limits he had on cruising grounds, so it seems to vary wildly. The one broker I called never called back to quote me after taking my info and I haven''t followed up yet.
I am in Puget Sound so my info isn''t too relevant to your area, but maybe it will help somewhat.