Hello Mabman,
I have been getting mine from http://www.retrophotographic.com/minox.htm. They're UK based so I don't know if they will ship to Canada, couldn't see any shipping info on the website without actually creating an order. No harm in dropping them an email.
The bloke behind http://www.submin.com/8x11/index.htm used to sell on ebay, can't remember his name but one could identify it was him by the patterned backgrounds he used for is product photos. I bought my developing reel from him.
Sorry they're UK-centric but it might help.
Cheers
Crispin
P.S. I keep all the used cassettes so I'm ready to slit and load should the availability suddenly dry up.