Actually it may very well have only been $15 per person back two years ago. But now even the their costs for buying liquor have most likely gone up. Plus you are not figuring in the rise in prices of fuel, food, soft drinks, docking fees, etc, etc. (when fuel prices rise, so does everything else we consume.)
Two years ago I believe I was paying almost $1.25 less per gallon of fuel. Two years ago I could fill up my van for under $25. Today that cost has doubled, and earlier in the year the figure to fill up my van was around $60.
So his figure from two years ago most likely is accurate. Having owned a business in my previous life, I know that if a business is to survive, they MUST pass on that cost to the consumer or they will go under.
You may be disappointed but it seems your disappointment may be misdirected. Be angry at the rising prices of fuel because that's what is "fueling" the rise in prices of everything else.