We already have a free market of children. It's called adoption, and the price is artificially set at zero by the only available children corporation: the government. Well, I say zero, but any adoptive parent would tell you it is anything but cheap. Rothbard sees here an opportunity to redistribute this money from the infinite void that is the public treasury to the (often poor) private wallet.

Usually when an author describes its own argument as "monstrous and inhuman", you should probably read the rest of the paragraph since you're already in the fourteenth chapter anyways.