Hey Max B,
If you are going on a 4 night and you enjoy say a bottle of Beringer White Zinfandel. Go to your local supermarket or Sams and buy 4 bottles. It will set you back maybe $18 for 4 bottles. Don't worry about the corkscrew as they are looking for guns not a little wine corkscrew.
If you were to buy ONE bottle of Beringers onboard anywhere on the ship it will cost you $28.95. If you are enjoy a fancy wine that is not on this list
then you can bring it onboard and RCCL will store it for you and then charge you $11.00 to open it for you.
Do they offer a 4 day wine package. I'm not sure but expect to pay $120 for 4 nights if they do have it.
IMHO 4 bottles of Beringer brought onboard is $18 I will pry out the cork if I have to but my corkscrew is all ways in my suitcase.
or Pay 666% markup and buy it onboard