I once did the math, and if you drink 7 "premium" beers (Heineken, as I recall, was $4), or 9 domestic beers during the course of the cruise, than this is worth the $10 you pay for the mug (based on the $3.25 and $4.00 prices). We bought these on our first trip, and the mugs make a nice souvenier, but we've since decided that lugging the mug around everywhere was a bit of a pain, so we haven't bothered with them since.