From Duggar Economics: The Costs of 19 Kids in the WSJ:

When you add it all up, it’s not uncommon for a single child to cost a normal, middle-class family something like $1.1 million, from birth through the undergrad years. To get some perspective, the median price of a home in 2008 was $180,100. It is commonly said that buying a house is the biggest purchase most Americans will ever make. Having a baby is like buying six houses. Except that they don’t increase in value, you can’t sell them and after 16 years they’ll probably say they hate you.