As far as purchase price for liquor is concerned, yes, you can get some good duty-free bargains. But I've never bothered. One of the most amusing sights you can see as you stand by the rail before leaving port is some sweat-laden passengers straining and groaning as they lug cases of "bargain" booze to the ship. Most of it is stuff they can buy for just a little more when it's on sale at their local Walgreen's. Many tourists get "buyermania" when travelling whether the purchases make sense or not.
Then, when these folks' cases or multiple bottles of liquor are delivered to their cabins the night before landing in home port, they have to figure out how they're going to pack them, carry them, haul them through the vast baggage pick-up area, through customs, and then how to get it on the airport van and then on the plane or however they're travelling.
I only bring home a bottle or two of Jamaican rum punch or whatever because some specialty liquors are hard or impossible to find in the States. I love to serve icy, fruity rum punches to company in my Florida home. I even buy some little packages of hanging monkeys and umbrellas to bring home to decorate the drinks!
When I'm packing for the cruise, I always leave extra space in a suitcase for a couple of souvenirs. I also pack a couple of folded up shopping bags that I can fill and carry off by hand upon disembarkation.
Of course, you can buy a couple of cases of adult beverages at these shops, and they will ship it to your home in the States. But that's expensive, so there's no point in doing so.
Prosit!
Bahama Mama