Autograph Fashion is an Australian plus size clothing store that is new to me. And guess what, they deliver to Canada. There is no flat rate listed and costs are dependent on location, weight of package, and method of shipping. At the moment of this posting they offer free shipping if you spend $100 (easy enough to do) even to international customers.
They carry sizes 14 to 26 but definitely read their sizing information before you order. Prices are shown in Australian money when you first visit but you can change the currency with the drop down menu in the top right to Canada or the US.
The prices do not fall into the budget range meaning a dress will probably cost $90, a top $60; unless it is on sale. I follow a few Australian bloggers and they absolutely love this store.
* Get your plus size fashions from Autograph