Larrysmith, 1/2 the fun of collecting is the hunt for whatever you're looking for.
As others have mentioned the EE, and several site sponsors are great places to hunt for milsurps. Also gun shows can be a great place to buy IF you know your stuff and can decide what a piece is worth and weather it's genuine or not. 8ve met guys that have been on the hunt for a paticular rifle sometimes for 40 or 50 years.
Lastly this hobby is about patience as most of these guns have not been made in 50-60 years so it's not often that anyone finds a stockpile a of say mint P17s in a bunker somewhere. It does happen but that is a rarity rather then the norm.
I've only been collecting for 3 or 4 years and already I've made so many friends and contacts in this comunity that more often then not guns just seem to fall into my lap if I'm patient enough.