As for overnight stays, there are lots of opportunities for free-camping. Pitching a tent for free on state-owned land (what we call "Crown Land") is legal for Canadian citizens (but nobody checks if you aren't). Motels and B&Bs tend to be very expensive in Newfoundland especially in the summer. While St John's is booming, the rest of Newfoundland, especially the old one-industry towns have suffered in the past years with plant closures, which has rippled into the motels/hotels because of lack of off-season business.
As you travel through Quebec and the Atlantic Canada, look for college or university residences for affordable accommodations. I've stayed in a few of them: McGill U in Montreal, Laval U in Quebec City, the CEGEP in Rivière-du-Loup, St Francis Xavier in Antigonish NS, and Memorial U in St John's NL. There are a few hostels in the cities, and I think there is one in North Sydney NS where you take the Newfoundland Ferry (I just slept in a park overlooking the docks because my boat was leaving in the very early morning)