I know with Nikon lenses you don't even get the original warranty buying one used, let alone the free 4-year extension to the original purchaser who registers it. So, it's worthwhile to buy Nikon lenses brand new. Brand new the 10-22mm can be purchased from
The Imaging World for $666.95 USD. You could call Joel Weiss, the manager there at (718) 218-7903. He can sell a Canon lens to a Canadian; the warranty is valid in the US and Canada (not so with Nikon). He also said an imported lens does not include a warranty for Canada and used lenses have zero warranty.