There are All Inclusive options available--Soda Package and several levels of alcohol packages starting at $14.00 USD Per night ranging up to $54.00 USD per night.
I'm a non-drinker, but don't mind sharing with a moderate drinker.
One of the group members on the last group cruise I did saved all their receipts and added up all the regular charges against the all-inclusive price and said they saved a couple thousand dollars. I'm hoping my roomy wouldn't be saving quite that much:-)
My sister usually throws a cocktail party or 2 during the cruise. Not sure if she's including alcohol with so many buying the package deals. It's usually a fun gathering.