More debunking the children's literature

So I was able to find 1969 retail prices for most of the basic food items you'd use to make cookies here.  Someone more enterprising than I could probably figure out the utility cost of baking a dozen cookies using the other data provided. Although there were some gaps in the data, I came up with this:

1969 Price	Ingredient
0.06	3 cups flour
0.06	1 cup granulated sugar
	1 1/2 tsp baking powder
	1/2 tsp salt
0.42	1 cup soft butter
0.05	1 egg, slightly beaten
0.01	3 tbsp cream
	1 tsp vanilla
0.49	Cost for 24 Cookies

Which, of course, means that the ingredient cost alone would exceed two cents per cookie on the plain sugar cookies, let alone the Peanut Butter and Chocolate Cookies we are also informed she counts among her wares.  So we have now thoroughly established that Mrs. O'Brien, while charming, was obviously not in it for the money.