Right handed or Left handed? You can look at the Galco or Bianchi websites, but the selection for Western style holsters is limited. The custom houses, sites that specialize in Western leather craft and leather goods, are too expensive for my taste. There are several on the web: Historical Emporium and Cochise Leather to name a couple.
Amazon probably has as good a selection as anybody with reasonable prices. Do you know a leather goods store close to you that could make one for you? They may have catalogs with kits. Show them a picture of what you want.