What I do, and believe me I make barely over minimum wage at my job and have a small farm that I support and work myself, is the following:
I buy the best chicken feed I can...pelleted. I buy cheap dry cat food and mix it with the chicken feed, along with BOSS that I buy fairly cheaply for the goats.
Unfortunately, I live on 1 acre so I have NO room for storage and can't buy bulk. We don't have feed mills and this state doesn't really grow much except oats. I buy whole native oats (11.00 for 80 pounds) and mix it with the goat, horse and chicken feed to stretch it a bit.
The chooks get house scraps. I also cook up stuff for them, usually high fat treats in the winter. I watch for sales on bird seeds and cat food and get that on sale when i can. The pet bantam eggs or the frozen winter eggs get used for food for the chickens and the dogs. I hard boil them and smash them up for the chooks-nutritional meal with added calcium. I don't have to buy oyster shells that way.
My friends save me chicken friendly table scraps and eggs shells. I occasionally get old bread at the dead bread store. I grew veggies for them, but they wouldn't eat them so the dogs got 'em.
I make my own healthy treats out of left overs or sale items from the store. I also go to the dollar store to buy canned fish and such really cheap for the dogs and chooks.
I also make 5 live culture yogurt for the chooks and the dogs out of the extra goat milk.
Sure, I can't afford to have these critters, but I consider them "pets with perks". The chickens provide eggs for me, the dogs, the chickens and my friends. The goats provide milk and milk products for me, the dogs, cats, chickens and anyone else who uses the soap/yogurt/cheese etc. I know my animals are healthy and happy and fed a good healthy diet. The dogs keep the wild life away and help haul heavy stuff (sled dogs). They help me up the stairs (really bad knees) and out of chairs and such. Plus, they are my babies who provide unconditional love. The cats and horses don't really do much of anything, however their care keeps me up and moving even when my joints are screaming in pain, so they do help to keep me healthy.
You can also raise your own live bugs for supplemental feed for the chickens......cheap to raise. Use your imagination and believe me, you will find ways of keeping your girls healthy, happy and producing.