I don't think it's a valid comparison to current prices. For whatever reason chicken was expensive back then -- fewer chickens, maybe? So it would stand to reason that eggs were, too. We seldom ate chicken. In fact, one of my favorite things my mom made was "city chicken," which was veal (!) shaped to look like a drumstick with a stick inserted in it to represent the bone. It came already breaded and she fried it. It wasn't until the 60s -- because of mass farming of poultry? -- that we ate actual chicken more often.