It depends on what you do. To get the same nutritional value for every bite like a commercial feed pellet, yes it would probably cost more. But you can have perfectly healthy chickens without giving them carefully measured nutrients.
The biggest, most important thing you must remember, is chickens are omnivores. They require a wide variety of food to remain healthy. You, like me, free range that helps. But it will not completely see to all their needs, you just do not have enough space. In the winter months I feed my birds meat once a week (back 60 years ago that was one of the farm boys jobs, trap something for the chickens to eat) I just give them enough that they can quickly eat it in about 10 minutes, generally I feed them organ meat. I also offer a wide variety of kitchen scraps (I have 2 toddlers so have more then most) you also should add a variety of grains, if you look you will find a thread that discusses homemade chicken feed recipes.
Homemade feeds and commercial feeds are comparable to a person on a very strict diet that ensures they get exactly what their body needs, no extras, no deficiency. Compared to someone with a more casual eating style, someone who eats healthy, but sometimes they more of one vitamin and less of another. This is OK as long as next time they get that vitamin. Chickens, like people, survive very well on a casual diet. As long as it is varied, and you keep you in mind what chickens can eat, and what is toxic.