I know nothing about the shipping to Canada, other than others have reported it's expensive, but my LHS here in the Midwest US has been able to get me straights and curves all along when I needed them. They just got some 10" straights to replace the ones they had until I cleaned them out a few weeks ago. Switches are a totally different story, those are quite difficult to find.
As others have said, Atlas has had difficulties with their Asian manufacturers and have switched to different factories. They are now caught up with their HO & N track (at least at my LHS anyway) and hopefully the O track and switches will be coming soon. My LHS was out of a lot of Atlas HO & N track for quite some time and could not get any from their suppliers.
You could also try posting here in the 'Wanted to Buy' forum if you are ok with the idea of purchasing used track. You might even flush out some switches that way?
