I have two listings in Canada, both in B.C. and both in Chilliwack, BC.
Grey Cat Farm Nursery at 4610 Simmons Road. V2R 4R7 (604)823-4780
and Mosterman Plants at 43583 Adams Road V2R 4L1 (604)823-4713
These are listed as nursery sourses in the back of 'Japanese Maples' by JD Vertrees and Peter Gregory.
My local source is forestfarm.com and they say a phytosanitary certificate is required and to ask for details.
These are tree sources and not bonsai sources, just want to be clear on that, but I get alot of bonsai material from Forest Farm Nursery. Check out their catalog, many rare and unusual trees from all over the temperate regions of the world.
Hope that helps you get your trees, Rick