Royalcruiser, I've never bought the package either, but I believe it's like you explained. You get to select from the wine menu, and they have different catagories with different prices. I have seen them set up in front of the dining rooms on embarkation, but I've never signed up for it.
Your cruise is coming up in no time. I've heard very good reviews about the Golden. Hope you have a marvelous cruise!