Porter-Cable's website has a dealer locator too. One or more of the dealers in Winnipeg should be able to order you a PC and counterweights. The Meg's dealer can get you a backing plate.
You can find meguiars stuff at Napa Auto Parts stores. I order my meguiars stuff from the one on Panet Road and Dugald. They have the professional catelogues, and can get everything including pads. I've ordered #83, #9, #7, #16, and in the future #80, and some yellow polishing pads.
