Neither Canada Post nor Paypal support shipping labels for LetterMail, as you probably already know.
If you buy postage stamps at the PO you will pay 85 cents each for those in booklets plus GST.
(Buying them one at a time costs 85 cents+ 15 cent service charge +GST)
However, the Dominion of Canada has never demonetized any stamps. Any mint stamp of the Dominion of Canada (or Newfoundland) is still valid for postage.
You can buy postage lots on eBay and in philatelic auctions for less than face value. You may also get Free Shipping (really meaning the shipping cost is already in the asking price) and no tax charges.
