First time sailing with Carnival, do they have packages you may purchase for wine/beer etc. Other Lines do have specials example, if you by 15 beer you get it a little cheaper as the wine by buying 3 to 5 bottles it is cheaper.
Yes, the buckets of beer saves you some money, but I think there are 5 bottles in a bucket (and you pay for four of them??? its been a while) so unless you have help drinking them, they are warm before you can drink them all. Of course you could always ask your room steward to empty your cabin fridge and buy a bucket and store the bottles you don't drink in there for later consumption.
As far as you original question, they have the wine packages but unless they recently started offering them, no beer packages... you can check their website for sure. They do offer a drink coupon booklet but you don't really save money using it, its meant to be a gift for someone to buy you.
Did you notice if they offered the "Drink of the Day" card on the cruise? I used to get the bucket of Coors Light 12oz cans, but they switched those to the 16oz bottles as well. At least they were plastic and had the screw on tops. They actually stayed pretty fresh when I would reseal one.
If you get the Bud products they come in aluminum bottles with pop tops. So if you are going to take any back to the cabin it is a good idea to have them only what you are going to drink, and bring an opener.