Nyt,
We have two major ones, one more so, and more major that the other; allrocketengines.ca out of Toronto. He carries pretty much all you need, Madcow, Aerotech, PML, etc.. And there's Coastrocketry.com out of Vancouver. he seems to mainly focus on kits, mainly LOC, a few Binder and also PML. Angelo at Sunward is also a player, but is more suited to motors (CTI). Local hobby shops typically Estes, and never have the sales Estes online shop have.. Even then, it's limited to what's hanging on the hook, or what can be ordered thru them. I would also mention GreatHobbies.com, but they are typically only Estes / LPR stuff. (But if you are into R/C, they are you place!!) I believe there might be one or two other places that do mail order.. but I personally haven't looked too hard. (Allrocketengines has been my recent go-to place, or the local hobby shop..)
Then, there is ordering directly from the US. Sometimes a vendor will mark "$50" on the customs claim when in fact it's slightly higher.. I think I've paid duty twice getting a US mail order. The real killer coming from the US is vendors not willing to ship USPS, as UPS & Fed Ex essentially rape you for duty & brokerage fees, on top of their shipping costs.. There is also the ability to get a 'Kenik' address,
https://www.kinek.com/how/ but you need to be somewhat close the border, or their receiving house in order to pick up your package. (Kinek is essentially a PO box with a US street address) But, you do then pay the exchange rate of the day. And, it is in the US, so no motors (unless you fly them in the US - that's what we do). And you do run the risk of paying taxes & duties if you're only in the US for <24hrs..
Now, let's talk clubs & certification. CAR is the governing body up here. And things are a little differ that the US. level 1 is H motors only, and you need to do a written test. A portion of the test is Transport Canada regs, and is a government requirement. Level 2 gets you I motrs, no test. Level 3 gets you J-L motors, again no test. Level 4 is like NAR / TRA level 3; documentation, proofs, inspections, etc.. And clubs, from what I've seen, are few & far between. So, while I have my NAR L1 (and hopefully L2 later this year) I am not allowed to fly anything above a G in Canada until I pass the Transport Canada portion of the CAR L1 Test.
https://canadianrocketry.org/