All gas is priced in litres in Canada and have been for about 20 years. Prices in BC are amongst the highest anywhere. It gets confusing converting because you have to remember that the Imperial gallon is larger than the US gallon.... roughly speaking there are about 4.2 litres to an Imperial gallon and 3.7 litres to a US gallon.
So just forget out imperial gallons altogether and whatever price you see in Canada.. say $1.00 per litre reduce it by say 10% (current exchange rate?) which gives you 90 US cents per litre and multiply it by 3.7 to give you the price in US gallons.
The other thing to remember is that for evey penny increase on those signs outside the gas station..is actually 3.7 cents more per gallon,, makes quite a difference when the price goes up 5 cents etc.
It's gonna cost you about $40-$50 Cdn to fill up an average car on regular. Still cheap considering what they pay across the pond.
BTW you should have been visiting over the last 10 years when our dollar was worth only about 65 cents...too late now though it's up to 95 cents roughly so you won't bag the bargains you could have..