This is a list of Canadian suppliers (or places that will ship to Canada) for a variety of things, as our needs tend to be rather esoteric to find in a google search. Please feel free to add your favourite suppliers to it.
Gemini Fibres Located in Ontario. Dyes, mordants, fibres, spinning, weaving & knitting supplies.
Embroidery
DeVere Yarns (Embroidery silks, including extremely good stranded silks)
Sew Fancy (Located in Guelph, specializes in hard to find supplies, including Japanese-made needles)
Thistle Threads (Embroidery silks (including stranded silks), spangles (both regular and bobbin lace), silk gimp, braids, goldwork supplies (including the only place I have found #4 passing thread)
Pergamena US supplier, ships to Canada. Vellum & Parchment. Selection, quality and customer service all excellent.
John Neal Booksellers US supplier, ships to Canada. All the supplies, lots of specialty SCA supplies as well.
L. Cornelissen & Son UK supplier, ships to Canada. All the supplies, including a large selection of gold leaf. Often shipping from UK, via Royal Mail, is significantly less than shipping from the US. Note that website prices include 20% UK VAT which is not charged to international customers.
Gold Leaf Supplies UK supplier. The online ordering will not allow you to select shipment to Canada, but you can email your order to them and arrange payment via bank transfer or paypal. (They cannot ship oils or solvents to Canada, which is why their website doesn't support it). Shipment is via Royal Mail. Their prices are good and they have hard to find items like heavier 24ct leaf, a large selection of shell gold and specialty items such as shell lapis.
Kama Pigments Canadian Supplier. Shell and leaf gold, as well as pigments and dyestuff. Watch if you are shopping in English, the site sometimes punts you back the French side.