Where is a reputable source, preferably in Canada, to purchase?
Source for which vape? The PD you can only get from vapenow.com, and they do ship to Canada (there is a wait time for delivery, currently 6-9 weeks-worth the wait though). They also sell the other vapes you mention. Any US vendor or manufacturer will be shipping postal to Canada. Rockwise.net (Canadian) is your best bet for the Extreme. Vaporize.ca and Vaporizers.ca are both good Canadian dealers. The latter has been in business a lot longer. Also check eBay. These dealers and others sell there and you'll usually save a few bucks by going through eBay.