If they stick to hotels and bars in upscale areas, visitors from Western countries (with the exception of Scandanavia) will find Japan an expensive place to go out for a few drinks. The language barrier can be a bit intimidating but a visit to an izakaya or one of the other cheaper drinking spots will pay off, both in terms of price and cultural experience. Other bars and western pubs are more expensive but have a more familiar atmosphere. As for the infamous places where you get charged an arm and a leg for a beer and a few peanuts, well, you should be able to spot the difference as soon as you walk in the door.
(Incidentally, store prices haven't changed much in recent years - where they have, they've generally come down - and imported beers are often cheaper to buy in convenience stores than domestic brands)