I thought the butter was in there? But the bread makers are pretty efficient energy wise, especially in the winter when any excess heat goes to heat the house. The person who wrote that said they deliberately omitted the water cost as negligible (which it would be here even for a season of use).
A relative of mine was a food processor. He sold Ivanhoe mayonaise, and in 1934 published the recipe as part of his advertisements. The ingredients worked out to 30 cents a pint for someone at home. It sold in stores for 32 to 35 cents a pint at that time, and provided a jar that was useful for canning afterwards. In the quart size it was 50 cents.
How could he do that? As is common today, he worked with suppliers to cut their costs, had other products that used waste (his mayonaise used egg yolks, and he had other products that used the whites) and made his product in large batches with purpose built machinery.
http://www.hoxsie.org/2013/03/make-your-own-ivanhoe-mayonnaise.html