Dunn's is available in Calgary. I had it in Montreal years ago, but I seem to remember a slightly different taste.
Dunno Sam's.

Kickers Deli in Calgary has a full cut for $12.99, regular cut $10.99.
A twist is Miss Montreal on rye- smoked salmon, cream cheese, red onion, lettuce, tomato.
There are other places, but I don't know anything about them.

Dunn's is sold at Costco if you want to make the sandwich at home.

I have a pouch in the fridge, but maker unknown (from a deli in my neighborhood).