Site sponsor: Marstar, might be a good place to start. The site offers a variety of western holsters and gun rigs. Another Canadian source: Last Best West, out of Calgary. A quick Google search for "cowboy action holsters" will turn up quite a few other sources. Such as: Mernickle, Kirkpatrick Leather, El Paso Saddlery, Doc Noper, Tombstone Leather and many others. All top quality gun leather makers. These are all in the U.S., but do ship to Canada. There are plenty more not mentioned.
As mentioned, if handy with tools, you can always make your own. A simple process. Many examples of the process, on you tube.