You will find the drink prices to be about the same as you'd pay in a regular restautant, just remember also that they will add the 15% tip on to you bill, so no need to tip any extra. Everyday, they will have a "drink of the day" and you can save a little if you like any of those, just check in your daily compass, it will tell you wha that drink will be, have fun!
If you are into wine at dinner, there is a wine list on www.mytravelco.com. You can select Cruises and from their you can find your ship. I don't think they have lists of other bar beverages. Although, there is lots of other information too.