I can buy seeds from companies in the USA , but they have special clearances with Canada's Agricultural bureaucracies.
Some of the smaller USA companies can not afford to jump through the hoops so they can not send seeds to us.
I can not send seeds to the USA without the person getting a Phytosanitary certificate from US Agriculture.
The NARGS organization does this for the Seed Swap so I can send seeds to them.
I was disappointed this spring to find that Botanical Interests could not send seeds up here.
I used to find their seeds in local garden shops, and also I could place orders and they would ship them.
I am hoping that they are able to "jump through the hoops" and we can access their seeds--- which I really liked.