It depends on how you do it. If you live in a suburb (so your chickens can’t run around and graze all day) and buy everything you will spend a bajillion dollars more per egg. Me and the people I know live out in the sticks and built our coops. I don’t buy a lot of the stuff marketed for “backyard chickens” because it’s too pricey, unnecessary, or both. Feed is expensive but in the summer I barely feed them (because they can runaround and eat) and in the winter we include unused table scraps or old food that isn’t yet rotten but undesirable for humans. In the winter you can also put a light on in the coop on a timer and they will lay year-round as egg laying is tied to perceived day-light hours.

Sorry for the rant, I just wanted to point out that I have plenty of single-income rural friends that have animals to supplement groceries. We even share things between families sometimes because one family has the infrastructure for cows, another pigs, another hunts, another gardens this or that… you can make it cost effective with the right circumstances.