Impossible to say unless you are more specific. Some are more expensive than a pub, some cheaper and some don't charge. It is the least of your problems when choosing a cruise there are too many other variables (unless you have a problem). ..... Neil.
Ships like our pubs charge different prices but a rough guide is as follows
Spirits i/e teachers whisky /smirnoff vodka / gordons gin is about £2.55-£2.60
Beer 1/2 pint about £1.30/ pint about £2.45
Cocktails about £2.95-£3.00
fruit cocktails about £1.75. I hope this helps you a little.
Unless you cruise with rci and then you can double these prices.