50 BMG just a few months back was easily had in milsurp for 2-2.50/rd, now you are lucky to find anything decent in stock at under 3.50-4/rd. Typically when it does pop up, it sells out faster than you can add it to a shopping cart and check out.
7.62x54r milsurp was ~65 per 880rd can now that's over 85 per 880rd can in just a few months. There's no manufacturing excuses for milsurp, it's just plain supply and demand. People are panic buying and suppliers are cashing in OR stock is running low. I don't know which really, but i'm truly fighting the urge to jump in because I feel (and hope) it's all panic buying so given time prices will fall back in line.