I've noticed from reading here on BYC, that the price of feed depends a lot on location. And of course, by brand. I pay $14.00 a bag for Purina Flock Raiser, and i think their Layena runs about the same. If i bought the "regular" brand from my feed store, it would run me $10-$12 a bag.
I paid $8.95 a 50 lb bag for scratch, (which the lady-birds did not approve of) and $12.95 a 50 lb bag for Layena by Purina. I toss in some scratch on the ground for entertainment purposes. They adore watermelon for more entertainment though.
I pay $13 for a 50 lb bag of Flock Raiser at my feed mill. $12.75 for a 50 lb bag of Medicated Start and Grow. $17 for 100 lb of scratch. I'm not sure how much the Layena or their own brand of layer feed is, as it is not high enough in protein for my birds.