CLC just might be your best bet, even with then currency exchange and shipping. Can supply both 3mm Sapele and 4mm Okoume.

I did a quick Google using Ontario Marine Plywood Suppliers, found a couple in Ontario as well as other outfits further afield so if you're set on buying Canadian you'd best do some calling/e-mailing, see if the can help supply what you need.

Before I discovered CLC I'd bought from Boulter, pleased with service and what they could supply but it's been 30+ years.... 

Noah’s is in Toronto (& Niagara Falls):

  http://www.noahsmarine.com/index.asp

I’ve purchased ply from them several times, shipped by freight to both the US west coast and Midwest. Good stuff.