My last cruise on HAL, and on my last cruise on NCL, cans of soda were $1.50 US. Drinks will range from $3.95 - expensive for some fancy martinis and blender drinks. Beers were running $3.50ish - but there is usally a special for buying buckets of 4.
I've cruised w/ HAL a few times now. Yes, Cokes can be very pricy. However, if you know you'll be putting back a few, they sell a card for something like $25 or $30 that you can show and get unlimited soft drinks at no extra cost for the entire cruise. A good deal if you're a big Coke drinker.
We just got back in April from our first cruise. It was on the Westerdam and it was amazing!! We did buy a coke card for $18, in the terminal before we even boarded the ship. It was good for 20 "cokes". It also comes with a really cool souvinier cup. I did find the average drink around $5-$6. It is pretty scary how fast your ship account adds up though!!!
We sailed with Holland last January, our second cruise with them. We were disappointed to see the liquor rules change. On Holland, you used to be able to buy liquor at the on-board duty-free and pay a 20% surcharge to take it back to your cabin - no limit! Considering how cheap it was, 20% wasn't much! All that's gone now. One thing one might consider with bringing liquor on-board, the rules don't apply to wine or champagne...I took a case through security without any problem at all. You can't take beer or any other liquor though. If your smart, you'll leave half your cloths at home and replace them with some "refreshments". We always do and have never had a problem. One other point, there is a big difference (not for the better) in sailing Holland now as to 10 years ago; all the cruise lines are out for every dollar they can get, with liquor prices and tips becoming ridiculous!
As of my trip on the Noordam in March, no unlimited soda cards. What is offered is a $18.00 soda card that is good for 20 soft drinks at the bars. Just the glass, no can.
If I recall, without the card a Coke was 1.75 but I think you got the whole can.
It was a good deal for me.