This is how I feed mine, I get a 50 pound bag of layer pellets (about $11.00 here) and mix it with about 1/4 of a bag of cracked corn (a 50 pound bag around here is about $8.00) The cracked corn mixed with the layer pellets makes the feed last a little longer and when you have 40+ chickens that is nice. I mix the corn and layer pellets in a plastic tote. And they have access to that all day in there feeders.
I also throw out some scratch in the pen when they come out in the morning (there is no need for a lot of this, its more like a treat) but gives them somthing to do during the day.
A bag of that goes for around $10.
Like I said corn is a filler & cheap (thats why you always see a lot of corn in dog foods) It fills them up for cheap $$. In order for chickens to lay good they need a good diet and layer pellets have everything they need in there.
Let me know if you need anymore help !!