Tutak,
Here are some sample prices from the Cruise Answer Book. I think all the prices are $2 cheaper if you purchase on board for all items.
Liquor (priced per liter):
Chivas scotch $37
J&B scotch $27
Jack Daniels whiskey $27
Smirnoff vodka $22
Beefeater gin $ 22
Bombay Sapphire gin $27
Bacardi Limon rum $22
There are also liquor and mixer packages - one 375 ml bottle plus three cans of mixer
Gin and tonic, Scotch and soda, Vodka and tonic, Bourbon and coke, Rum and coke, all $17 ($15 on board).
Wine, including sparkling wine and champagne, ranges from a low of $22 for Asti Spumante to $112 for Dom Perignon.
Cheers!