A friend of mine has kept chickens in his backyard for years (not for egg-cost reasons). He said he did the math recently, and given just the cost of feed (not including the up-front cost of building the coop, or ongoing costs to maintain it), eggs would have to go up to ~$11/dozen for it to break even. While I have seen eggs that high recently (at a small convenience-store type place in a relatively HCoL area), that's certainly still not common.