Oddly enough, when I went to my 2 local hunting supply stores, they had no idea what I was talking about when I asked about thungsten.
Then, of all places, I noticed Canadian Tire had some in store. Of all places!
Obviously, if you can find some at a sponsor, more power to you.
Quick trick, if you can't find some..., try searching on google for a canadian source of something with the following:
site:*.ca thungsten shotshell
The "site:*.ca" will match all addresses that end by the .ca (prohetriver.ca, wolverinegt.ca, etc, etc)
David