I have learned that Connecting Threads collects tax and takes care of duties, so I do not have to worry about paying extra on their packages. I also get free shipping from Connecting Threads, the only US company that has offered free shipping to Canada.
I think Craftsy does too as I have not had to pay tax or duty on packages from them either.
I am expecting a fairly pricy package from MassDrop after Christmas I am waiting to see what I may have to pay them.