Well you could do what I did, lurk around a lot of forums watching for brass for sale. Over the past year or so I've acquired almost 1500 pieces of mostly new 7.62 x 39 brass, and never paid more than 25 cents a round for it. A couple of years ago I also bought some for about 30 cents a round until I got smart and started waiting for it to pop up on forums.
I wanted to have a stash of good, accurate, dependable, non-corrosive ammo that I could use for.........well, anything, if you catch my drift. This is the way to do it.