You can save some $ by purchasing your alcohol at the duty free stores of your last airport before leaving the US, CLT in your case, or bringing from home.

Per person Duty Free limits into Cayman:
1L of Spirits/Liquor
or
4L of Wine
or
1 Case of Beer

Tap water island-wide is desalinated and safe to drink.

Snorkel air just tastes better than canned air...