I dunno, this is different from what is stated above...
Passengers under 21 years of age are not permitted to purchase or consume alcohol onboard. Duty- and tax-free alcohol is available for purchase and may be delivered to your stateroom the last day of your cruise. Discounted stateroom packages are available. Click here to download our beverage menu.
375 ml - that's larger than an "airline bottle" and smaller by half a "regular bottle". The unit of measure that replaced the "fifth" in our bars and liquor stores and that is commonly seen is 75 ml. You can get 12 "shots" from a 375 ml bottle. So, those prices are higher than a liquor store but not outrageous AND you can "do it yourself", in your cabin whenever you wish without the 15% fee.