In 2013 we needed to fuel around the Pink Mountain area, here is where we paid when you changed from liters to gallons over $9.00 per gallon. We met many folks from the lower 48 at the various campgrounds that were very upset with prices in general for everything from food to fuel who swore they would not spend a dime in Canada that didn't have to. Considering that many of the business in NW Alberta to Northern British Columbia and definitely the Yukon depend on the tourist trade they sure try to wring out every cent they can from you. But you know all that said the trip to our 49th state is worth every cent, I didn't let this ruin our trip in 2013 and will not be surprised in 2015.
Canada has high fuel tax which causes virtually everything else to rise. Being prepared and knowing about fuel prices and longer transportation distances for everything should set expectations on price.
If you have to buy fuel at Pink Mountain ($6.50 when we went by in 2013) they buy just enough to get to Ft Nelson where it's only $5.59. Ditto for Beaver Creek, get enough to get to Tok. Note that Alaska border town fuel price is also very high.