Vitacost.com
They are from the U.S. but every two weeks or so they have a buy one get one free offer on their own brand, which includes stuff like magnesium, b12, zinc, and all that. They are already slightly below normal prices, so the BOGO makes it twice as low cost as anywhere else. Shipping costs $9.99 to anywhere in Canada.
Usually they email 10-12% off coupons, or they give them with your order. You can also ask for one and they will probably give you one. Comboing BOGO and the 10% off, they are still more affordable with the bad CAN dollar.
For methylfolate I'm using methyl-life. Vitacost methylfolate doesn't come in high enough doses.