I guess we are just lucky. We just recently added a 7th pullet to our flock, but we've had 6 hens for about 9 months now and don't go through very much feed at all. We have gone through half a bag of chick starter, one 50-pound bag of flock grower, and just opened a second 50-pound bag of flock grower (I don't feed mine layer pellets--they get the higher protein flock grower/meat builder-type stuff with free choice oyster shell). That's all the feed we've gone through in 9 months. They forage all day, plus we do give them scraps and treats (they are fiends for leftover rice or oatmeal or steamed veggies or scrambled eggs), but our feed costs are really nominal when we consider how much money we spend on our OTHER hobbies!
This week, the girls have been happy helping me turn over the ground in prep for the garden, and there have been so many worms and other things in the dirt--it's like Hometown Buffet (similar to Ryan's to you folks down south) for chickens!