I was told by Cinestill to contact downtown photo in Toronto and Gosselin in Montreal to express interest in them bringing in the kits, which I have done.
Shipping was $28.00 USD. I will have to pay 5% GST when it gets here. As no photo chemicals are made in Canada there must not be duty, but I expect a brokerage fee.
That is cheaper than shipping to Montana and picking it up myself.
That actually isn't at legally or practically related to whether or not there is any duty payable.
However, as the chemicals are made in the USA, it is most likely that the replacement for NAFTA will result in there being no duty.
The same would apply to chemicals made in Mexico.
I'm still using the first 1L from the Kodak C41 5L kit. 12 rolls of 135/120 film so far, and the negatives look good and scans well. I have not detected any color shift or contrast issue yet. Bellini was my reference.