I haven't seen it at any of the usual places and a quick check of kingarthurflour.com 's store locator doesn't have any Canadian options... Looks like you can order from their website, though shipping costs might be prohibitive: International orders: Please call for shipping quotes: 800.827.6836.
Just a little more info.
From an article in the Montreal Gazette
"As for the Vermont store, it is called King Arthur Flour and they do offer excellent flours and baking goods by mail order. However, there is a postal charge of $15 on all Canadian orders, and they could not estimate the cost of any taxes that could be added once the parcel crosses the border."
There is a local independant miller that produces beautiful stoneground wholegrain wheat flour - JRK Farms in Three Hills, Alberta. Not sure where you can get this store wise as I get mine from industry contacts. Anyone seen JRK Farms flour on the shelves?
JRK Farms Three Hills, AB Phone: 403-443-7317
Three Hills, AB T0M 2A0
Phone: 403-443-7317 Fax: 403-443-7081
Toll Free: N/A firstname.lastname@example.org
# of Employees: 1 to 25
President/General Manager: Jim Hugo
Products: All Natural Whole Grain 100% Stone Ground Flour (Wheat, Barley, Rye, Organic Spelt)
Brands: JRK Farms 100% Stone Ground Flour
Sorry I haven't... although I'm keen to try anything local so I'll have to look for them.
There's also Highwood Crossing from Highwood River, south of Calgary. They grow and process their own organic flours, oils etc. I quite like their w/w and all purpose flours myself. For where to buy info: http://www.highwoodcrossing.com/avail...