I have only bought chicks, at about $3.00 each. I have never paid for adult laying hens. For me, it just makes more sense to replace an older sick hen with a younger chick in good health. Last time I was in the vet office was many years ago, and minimum charge was about $80.00. That would buy a lot of days old chicks. If someone keeps chickens as pets, and wants to spend the money on a vet visit for a sick hen, that's OK with me.
My third year hens have more or less stopped laying eggs, so it now costs me more to feed them then I can ever expect to get back in "free" eggs. I have really enjoyed my backyard flock, but they will have to be replaced in the spring if I want more eggs in the future.