What's top shelf for you? Do you mean organic?
Yes, my chickens free range too. While I don't buy expensive food, I do make sure its good quality and reasonably fresh. I will buy the Purina Layer for $14.99, or Nutrena Layer for $14.50, depending on which is on sale. I go easy on the scratch so can't remember how much it was, but thinking it was like $10.
I have 2 feeders, one with above mentioned layer pellets, and the other one is full of grower, flock raiser, meatbird, or whatever else catches my eye that day, with calcium on the side of course. Those pellets are usually around $15 as well. I don't think I even go through a bag a month with 10 adults, and 9 pullets. The foraging is good here as it never gets cold, so there are bugs / grass all year.