If cost is the supreme issue you gotta roll your own. There will be a significant cost of tooling up, but then...
I priced components for .223 recently and it came to “about” 23 cents per round... in batches of 2000. That’s about half price from the cheapest ammo available we could find. We reload everything but rimfire. I “think” I have my notes on the places I found the components....if you’re interested.
Have to agree with adding if you don't reload, you can't buy due to scarcity of some calibers.
Less than $40 @ Cabelas. You'll need dies, scale, powder, primers and bullets.