When my last Manx died in 2004, I too couldn't find a registered Manx, so I went to my second breed of choice, Devon Rex. They're more active but not as chatty as my Manx were. The Canadian Cat Assoc. does not have any Manx breeders listed. http://www.cca-afc.com/classified/index.php?
I did see some black unregistered kittens around Christmas time on www.kijiji.ca
and there are some Manx rescues on http://www.petfinder.com
in Toronto and area.