Sounds about right. I paid $4.50 for a warm (12 oz) can of Shasta root beer in Koliganek, AK.
Keep in mind that these prices are for very small, very remote towns where everything is flown in (or driven over the ice in winter), not downtown Montreal or Anchorage.
Root beer (well, Shasta at least) is a sugary soft-drink (non-alcoholic). I think I paid about S$12 for a pint of actual beer at some pizza place in Clarke Quay. Don't think they tax the sugary stuff as much (if at all?), but they'll certainly shame you out of them (hello TAF).
Certain foodstuffs are also more expensive on Caribbean Islands (not as high as remote Alaskan towns, but more expensive than the continental US). Brand names are also way more expensive there (for the most part) than off brands. Lots of Ultra Pasteurized products for sale as well.
