The least expensive feed (not cheapest) will almost always be a quality, local mill that grinds their own. A farmer type place, where local ranchers and farmers get feed for their herds, flocks and animals.
There is a horrible premium on buying fancy, pre-bagged, shipped feeds at a retail outlet of some kind. Purina, for example? $16-$17 at feed stores, rural stores.
Hubbard quality 17% layer mash at our local mill? $9.75
Unfortunately I did a search and there aren't any feed mills within 30 miles of here... I think the 'countrywide' feed is about £7 for a sack (20kg I think) but it's not good quality or organic. The one they have at the moment is much better but more expensive.
Does anyone know the ingredients of standard layers' pellets? Annoyingly they don't put them on the bag.
We've just moved house so our six chickens currently spend most of the time in our nearly finished 5x5 run. They are used to being completely free range but there are lots of foxes here. They have an hour of free ranging a day, and that will be more when the garden is fenced. Not much grass left in the run already, poor things
And feed- they have layers' pellets constantly in their feeder and I give them a big handful of wheat with cracked corn and peas around twice a day. Almost every day I make them some mush with oats, pellets, apple/pear cores chopped up and seeds and raisins mixed in.
When you get your livestock and hopefully dogs on line to keep foxes out, a great deal of nutritional needs for chickens will be provided not only by free-range pasture but spilled feed and feces of the livestock. Then you can get your flock to operate in dunghill mode which is manner domestic chickens have been kept for majority of the millenia while under domestication. The confinement alone using foods specifically for chickens is a very recent developement, 100 years tops for adult birds.