I see you are also in the midwest. Sure, we can garden and raise things the birds enjoy. But let's face it. 80-90% of their diet, apart from free ranging, is going to come from their feed, for most of us. A local feed mill often sells a locally ground feed for roughly half what a "rural lifestyle" store sells pre-bagged, fancy label feed. That's where the savings come from.
If I had to buy all the ingredients, along with a vitamin/mineral pack, I'd not save a penny. I know. I've done the math a dozen times. We pay $19.50 a hundred for a complete, 17% layer formula. FWIW.