Over the past 2 years I bought several 48 round boxes of surplus Greek and Canadian .303 from an elderly blind gentleman for $25 at the local gunshows. It was corrosive stuff, and I had a few hangfires with the Greek ammo, but all in all, my Enfields (my P14, and my 1905 Ross) digested it quite happily. I haven't seen him around for quite a few months now; this veteran always brought along interesting artifacts, not for sale-just for conversation. He had a complete Ross M10 rifle as well as an intact P14 at one show.
His wife had to poke him and tell him the stuff that I wanted to buy, that guy had some really interesting stories to tell!
I go to the shows now, and if I can find that type of ammo, it goes for $45 a box....it's a lot cheaper to use once fired Boxer, and roll your own....