That's a deal and sounds like a great trip.
But cheap skates
that we are, we carry some booze with us in our luggage.
The last cruise I took to Cozumel, the kids had to get a credit card for sodas, unlimited for $5 per day.
And you couldn't bring on any booze, although they sold it on board.
However one might bring on a big bottle of "cough syrup". 
The best time to get booze on board is in your bags when you first arrive. They just x-ray the bags
but don't open them. There is too many bags and too limited time.
When your ship stops at a port, you can purchase booze there but they confiscate it upon return to
the ship and send it back to your cabin on the last day of voyage. Same thing for booze purchased
on the ship. They hold it until the last day. And prices are very good on the ship, with no taxes.
So, one time our wives bought bottles of vodka in Cabo and poured the stuff into empty water bottles and
carried it into the ship without a problem.
"Money cannot consistently be made trading every day or every week during the year." ~ Jesse Livermore Trading Rule