With the way Jasper books up so fast online I would gladly pay the extra couple of bucks and phone it in. The rest of August is booked up solid online and last year even late September we were lucky to find a spot. Jasper is awesome.
A national park pass in the US costs around 85 dollars I believe...I will find out in September. But the quality of camping in a Canadian National park by my experience so far is better than the US National parks I have visited. Its not a knock to our neighbors down south just an observation.
In the end though I have absolutely no problem with paying extra to camp in a National park, state park or provincial park. Its the only time I smile when giving my money to any government. Its nature at its finest and you can't beat it. Although some of the boondocking pics down south in other parts of this forum look incredible. It sure beats some of the privately owned parking lots (so called "campgrounds") that I have stayed in over the last 20 years of camping.
Come to Canada...we're awesome!