I use Ritrama, I buy it from Willox graphics Vancouver -
In Toronto or Montreal, there must be some suppliers, or contact the mfg and find out who the distributor is for your area.
Ritrama, Duramark, Catalina, 3M, Coburn Corp., Arlon, Flexcon, Oracal, is Jac still around? these are just a few vinyl mfg.
I don't buy enough to get into it direct anymore. Easier to keep a couple of boxes here, or order sheets for a specific job.
You should look to the states, your dollar goes good and somebody pays the shipping at some point.
A real good way to find dealers is to go onto SGIA - Specialty Graphic Imaging Association and then their VTS (virtual trade show.) you can then type in a product, and it will give you a bunch of suppliers/mfg. anybody who exhibits at SGIA shows is on there. go to their website and look for ditributors of the product.