This is a utterly fantastic Scotch.
I've never seen this one. I live in Quebec too and they only sell the 12, 18 and 30 Y.O. (the latter at $326.25 a bottle. No need to say at this point in my life, I do not own one!).
They do, however, sell it in Ontario so I could easily get one. Did you try the 30 Y.O. and if so, did you notice a big difference between the 21 and the 30?