Dinghy Dock has in the past sold some decent beer in cans. At times he has had some decent beer on tap. It is pretty tough sledding to get a good beer on SXM, the change in climate also changes my taste. I have brought down my favorite beer, Johnny Utah from Georgetown Brewing in Seattle, and it just did not hit the spot like it does at home. I can only handle a few "island beers" before I tap out and go to cocktails.
Another vote for Dinghy Dock. A really good selection of beers - I can still taste the Left Hand Brewing Company's Milk Stout - and they have the best happy hour on the island. Half-price on all booze and selected food.