I got my latest O. briareus from
www.divertom.com He is a diver/collector and has them occasionally.
www.marinedepotlive.com supposedly has tank-bred O. bimaculoides occasionally, but they offer them from a few different locations so no telling really. Most likely their Western Americas octopus would be bimaculoides or bimaculatus, both cold-water species. I think they also sell Abdopus aculeatus occasionally. Eastern America's could be O. briareus, O. vulgaris, or O. mercatoris, maybe O. filosus (hummelincki) That's a wide variety of possibilities ranging from pygmy (mercatoris) to relatively large (vulgaris). Kind of a gamble.
www.liveaquaria.com sells Abdopus aculeatus pretty often, it's their Indo-Pacific species. Occasionally you get O. luteus though. I have no idea what their typical Caribbean species would be.
www.reefscavengers.com had some unidentified Nicaraguan species marked as bimacs, could be, but never confirmed it. Looks like something in the vulgaris complex though none the less. They also sell some other octo species but they are rare, expensive, and possibly endangered.
www.saltwaterfish.com sells O. filosus (hummelincki) occasionally but since Haiti didn't get its CITES info together in time this year any Haitian shipments might be limited or non-existant so that option might be out for a while. Shame, those are very cool octopuses.
There are more but I can't think of them off the top of my head.