Bulk buying their food saves at least 1/3 of the cost. If you don't have enough birds for that, team up with a few others.
Grow your own greens for them. Swiss chard works well and is cheap snd easy. Gdng the leaves up in bunches for them to strip.
Then choose productive hybrid hens, buy them at commercial rates (not pet shop prices!) and cull them at the same time as the big boys do.
Btw, we do none of the above, but that's the answer to your question!
. However, I get the feeling in this case that you already know more about this than we do, so please share more!