Some surplus Russian/East European 7.62 x 54R ammo can average as low as $.17 per round, from what I read (the box I ordered somewhere on the phone is about $.20 per round). The ammo is corrosive, but many people say there is no problem, as long as you to squirt Windex cleaner down the barrel after you are finished shooting, then later use normal Nitro solvent etc.
Just ordered two mail-order Mosin Nagants (bolt-action) on Monday, and both cost less than $100. You might go to "7.62x54R.com", etc.
Some pawn shop people (even former soldiers) mistakenly call them SKS. The shop asked $130/each for the 44 carbine etc, but the guy did not know what they were, or possibly had the names mixed-up.
Even some younger people in very good gun stores do not recognize the spoken Mosin Nagant name, although the store might have two of the curved-bolt sniper version, among numerous other old used rifles.