In regards to Argentix, if Jacques is low or out of something, just send him an email. The bad news is, you'll have to wait until the postal strike is over...could be a long wait though...
Jacques from Argentix.ca is a great guy. He will always help you out and answer your questions if you're not sure about a chemical or if you can't find something on his site.
He's my go-to, and I complete my needs with bits from Photographer's Formulary when necessary. Some stuff like hydroquinone cannot cross the border, but a lot can, though shipping's gonna cost you.