What you need to do is check the price list on the tables in the bars if you ask for Gin & tonic you will get the Saphire option whilst if you ask for Gordon's gin & tonic it will be cheaper around £5 [$7.20] but I always maintain the measures are bigger than we get at home i.e. 25mls The same applies when ordering a whisky or a rum etc be specific to the brand you want remember the waiters get 15% as a tip on all the drinks you order. Can't help with the beer but I think cans came in around £2.60 for 330mls but not sure, remeber you are in the equivalent of a 4 star hotel and back home the prices would be at least that if not more.
Last year on independence of the seas on the cruise to cork, the price of a pint of draught beer was around £3, probably a bit more now because of the exchange rate of the dollar, but enjoy the ship, its fantastic!!!!!!!
We sailed on the IOS in september to the med. As a Beer drinker I was appalled at the prices for a pint of lager. As I understood from my stepsister, who sailed on it in july, the price of a pint was $4.50 when the exchange rate was about $1.85 to the £1.00. However when we travelled the price had escalated to $7.50 per pint and the exchange rate had dropped to $1.70, making it about £4.40 per pint I thought this to be a tad over the top for a pint, especially P & O's prices on the Ventura in april were only £2.60 per pint for a better quality lager. My wife only drank soft drinks, the price of these were also about 15% more expensive than on P & O. I hope this is of some assistance.