I'll be looking to base myself in Vancouver soon. In the past, you've always had to prove at the border that you'll be leaving again, one way or another. Last time they didn't take the "I'm planning on winging it" comment well, so fortunately I had a bus ticket to Seattle as well (from Vancouver).
This time I'll have a return airline ticket, so that's easy, but I know other friends who just want the cheapest form of a ticket out of the country. Last time I had a $22 bus ticket from Vancouver to Seattle. Is there a cheaper ticket that would serve this purpose? Every dollar counts when you backpack ;)
Note - it doesn't have to be from Vancouver. Anywhere in Canada, to anywhere outside of Canada is acceptable.