This is where Point Roberts may be useful. I've started using a post box service there to get things that won't get to Burnaby... and it's a fun trip on Translink out to Point Bob.
It's extraordinarily useful for this purpose, and for our friendly southern neighbours who won't ship up here, even with us willing to pay the price difference.
I bought my silver nitrate in Canada from westlab.com which was the best option I could find. The price for 25 g is astronomical, but I bought 100 g so paid something like 2.90/gram. Translated to CAD you'd be paying about 1.83/gram from that Amazon seller so definitely cheaper, if they will ship to you. They won't ship to my location unfortunately.
If you do go with them please let us know how it turns out.
I just purchased some silver nitrate from Artcraft Chemical. I paid $34.00 for thirty grams. 100 grams is $87.00 and half pound is about $.75/gram very cheap compared to B&S. I get most of my chemicals from them and the quality, packing and shipping are excellent...no complaints.