You can get it in Canada thought it's nearly Unobtanium at prices nearly $0.36 a round with tax shipped at CanadaAmmo
There is Norinco at Tenda and Barnaul still at some dealers SFRC plus brass is always non corrosive S&B and Privi are good and avail from site sponsors. There is no secret gun store with cheaper prices the "in the know" people go to. Unless you consider that us meaning we don't buy ammo generally at Canadian tire, Wal-Mart or cabelas.
7.62x39 is still arguably the cheapest centre fire rifle loaded round in Canada both surplus and new factory steel. Brass rounds run a little higher than .223 but are still more affordable than other calibers