As previously mentioned, an original Model 1909 holster, half moon clip pouch, and pistol belt. A WW1 date holster should be fairly easy to find, but finding decent condition can be tricky. Make sure the bottom plug and lanyard ring are intact, they are very frequently missing. The clip pouches are getting harder to find, but a decent WW1 dated pouch should be doable. Woven canvas US pistol belts are surprisingly still fairly available, so do not settle for less than an excellent WW1 dated example. Mills made are desirable, but any of the other WW1 makers are fine.
You have to be careful on what you buy there, but ebay would still be a good place to start. Lots of reproduction stuff there, but decent quality originals can be found fairly regularly. The originals are somewhat pricy though. You need to be patient and bid on good quality items. Be wary of the high priced "buy it nows" that have sat there for months due to their overly optimistic asking prices. On the other hand, sometimes you can get a great "buy it now" item cheap if you stumble upon a nice item that is poorly described before other collectors see it.
If you do not like ebay, you might check other internet vendors with retail websites. Good luck, I find tracking down the proper accessory items to be a fun challenge. I try to get a correct holster, pouch (if needed) and belt for each of my US military handguns.
