Figure primers at a penny if you buy them in bulk. Figure powder at $0.15 (depending on which powder used and how you buy it)
If my math is correct that comes out to roughly $2.36 per round. That is $47.20 per 20 round box.
The hidden part is that once you have cases (largest cost) -- you can reuse them several times and recoup that expense so it becomes less expensive to shoot. Now, you know why almost everyone here reloads!