I've got 16 chickens, but only about half are laying hens. Got one standard game rooster, a bantam rooster, and 4 cockerels. So that's 6 non-layers. Plus a very pretty and apparently non-productive girl, I think she's too old to lay. So, only 7 layers, which is about right, since I get on average a half-dozen eggs a day. 
So I'm feeding 7 laying hens plus a bunch of extras. And a 50# bag of layer feed is lasting me 3 weeks at least. I give greens, leftovers, treats, daily so the layer feed is just a staple. I'm a great believer in giving plentiful greens every day, and I try to vary it, collards, cut grass, wild lettuce, etc. 
A 50# bag of feed costs me about $13. 
I'm getting 10 dozen eggs over the 3 weeks a bag of feed lasts me, if I sell them for $3 a dozen that's $30, half of that can go for feed. The other half of it can go in me. 3 eggs a day average. That's enough. 
So my little flock is pulling its weight! 
But wait, that's counting all those freeloaders. The 4 cockerels, the pretty but non-producing hen, and the bantam rooster are going to be sold. That's going to put a bag of layer pellets at a month or more. 
What it comes down to is, 7 hens are not going to eat enough to make making your own feed more economical than just buying your Purina or Dumor or whatever. They'll produce enough to pay for their feed, and give you enough eggs to eat too. 
Just my 2c.