I'd suggest finding a local chemical house and build a working relationship with them. That way they know you, and you know they will work to get you what they need. I've been buying random items from my local place for over 20 years now. Sure, they have to photocopy my drivers license to meet federal regs, but I'm fine with that.
I was able to buy a nice, explosive compound like Potassium Nitrate and they even shipped off a second bottle to a friend that was having trouble buying it. It may not have been the cheapest price, but it was of a known quality and that's important for what I was using it for.
For up from the ashes, up from the ashes, grow the roses of success!
You mean like mob rule, like the protesters shutting down the Ann Coulter talk at the U of 0 in March?
Yes - (after looking up the issue) - There is a scene in the BBC television adaptation 'The History Man' in which one of the students declares a talk should be closed down 'due to the court of radical opinion...'
There are almost no tariffs now between the US and Canada for goods that originate in North America.
As for the laws involved, I expect that US export restrictions are the only likely culprits when it comes to prohibiting shipping.
I'd be willing to bet that the reason it is difficult or impossible to get items shipped, is that there are bureaucratic and paperwork requirements in both countries, and that the task of fulfilling those requirements is an onerous one which no-one would willingly undertake when only retail amounts are involved.
It may also be the case that the requirements in the two countries are contradictory.
“Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”
Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2