Dual purpose New Hampshire pullets
I can understand why one might expect this to be true, given some of the fairly misleading information out there about raising and feeding laying birds. It is true that many breeds of chickens and ducks, particularly heritage breeds, can forage a certain percentage of their own food. However, the fact is that for optimum egg production, laying birds must have a consistently high quality of nutrition. This means that no matter how much they might graze or forage, they still need a daily ration of 16% protein layer feed.
Also, when the ground is covered in snow, there is not much for the birds to forage on. If you have snow in the winter, plan ahead and make sure you have adequate feed on hand.
One of our feed shelters
If you already have poultry (or any other livestock), you're no doubt aware of how feed prices have gone up since the summer of 2012. The Midwest drought affected the corn harvest to the point where even now, months later, feed corn (especially organic corn) is in short supply and quite expensive. Last fall our feed costs jumped by 25% all at once; the 1100-pound tote of organic layer mash we buy went from about $400 to $500 just like that. The formula changed as well, due to the shortage of organic corn and peas.
I know a few people who say they feed their hens nothing but kitchen scraps. Presumably these scraps are from something they either bought or grew in a garden; those are not "free" eggs.
We estimate that our laying birds, which are all excellent foragers, each consume an average of 1/4 pound of organic feed per day. We also provide them with crushed oyster shell, an important calcium supplement that keeps egg shells strong. When we have baby birds, we buy baby grit to add to their feed to aid digestion; older birds get plenty of grit in the course of their daily foraging.
Bedding is another expense. Keeping coops and nest boxes clean and dry is critical for the good health of the birds, so we use absorbent wood shavings and clean coops regularly.
So let's add things up: Feed, oyster shell, grit (especially if your birds aren't on pasture), bedding. Even if you don't take your time into consideration, those eggs are not only not free, they might be getting a bit expensive. And we haven't even mentioned coops, or the up-front cost of the birds themselves. If you buy day-old chicks, you will be feeding them for 5 or 6 months before they even start laying eggs.
Of course, the tradeoff is that they are super-fresh eggs that simply don't compare to mass-produced commercial eggs. Obviously, I'm in favor of raising hens and ducks for eggs. Just don't kid yourself that keeping laying chickens or ducks means a lifetime of free eggs for you and your family.