Even around Christmas, the wii fits and wii consoles were readily available here in Canada--or at least here in BC at most, if not all, Costco's, Toys 'R Us, etc. If you can find someone who might ship for cheap or for free? Maybe that's an option or a visiting friend or relative who lives in Canada? If you know someone up here, you may be able to get the console discounted enough to cover shipping costs if, say, s/he buys it from Superstore/Loblaws, they have a buy over $250 or thereabouts and get $30 off or some such (they change up the value every so often).
Just another option as I'm not sure if Costco.ca would fill Costco.com orders.