The OP was asking if it was possible to make enough money selling eggs to break even or even a little better. He/she was not asking about starting a sole business selling eggs as career type business. If you want to farm "Joel Salatin style" then I would absolutely agree that it is necessary to include labor, land, taxes, and even farm infrastructure. If you want to break even or maybe even make a few bucks from selling eggs from your flock I don't see how you could reasonably include labor, land and taxes in your figuring.
Since you, do however, feel that you must include these factors in your cost, I'll ask for the benefit of all for you to clarify. How much should one value their labor (time)? Do we use the rate the corporate producers pay? Do you value your time as the CEO or laborer or both since you do it all? What about land and taxes? Do prorate this amount based on what you originally paid for the land (even if the land wasn't bought for this purpose) by the amount used for egg production? What about depriciation for usage? How do factor this into your "real costs"?
I don't want to get too hung up on the accounting question. People correctly point out that they've already purchased their backyards, so why would you impute that cost to raising chickens in the backyard? That's a good point. My bias is to err on the side of strict fiscal accounting so that folks don't fool themselves into believing they're making money when, in fact, the opposite is true. The truth is very few backyard poultry breeders have any idea whether they're making money, breaking even, or sucking wind.
I would respectfully suggest that a true accounting, and a clear profit motive, is important for two reasons.
First, I think the more important question is that after the accounting is done, did your profit yield a reasonable return for your labor and risk? Maybe some people consider it fun to muck out a chicken pen, but I'm at the stage of my life where I wouldn't mind getting some payment for that extremely pleasurable activity.
Second, if you actually have a business plan and a legitimate business motive, suddenly your hobby is transformed into a business and all those expenses become tax deductible. So, if you're in the 25% federal income tax bracket, that $1,000 of chicken feed will only cost you $750 after you take your tax deduction. Not bad, right?
Let me close by saying that the vast majority of backyard poultry hobbyists are just that: hobbyists. They don't care about a profit, and that's fine. But, the poultry world is large, America is a free country, and people should be allowed to pursue a profit if they have the brains and initiative to make it a reality.
Fair enough. I guess I'd answer the OP by saying, "It depends" and leave it at that. My chickens have paid for themselves and then some - a very little "some". But my experience is just that my experience and what works for some may not work for others.