I have recently noticed that Expedia.ca and ExpedIaforTD.com now sell Air North tickets.
The YOW-YZF-YXY route can also be booked as a codeshare on the website of Canadian North - and, on occasion, that may be slightly cheaper than booking directly with Air North.
Allow me to correct the baggage info provided in the opening post of this thread: Included are well 2 pieces, none of which must exceed 32kg.
But the combined weight limit is 45 kg on Southern routes (flown with B737) and 20 kg on Northern routes (flown with smaller prop aircraft).