Now if a parent may own his child (within the framework of non-aggression and runaway-freedom), then he may also transfer that ownership to someone else. He may give the child out for adoption, or he may sell the rights to the child in a voluntary contract. In short, we must face the fact that the purely free society will have a flourishing free market in children. Superficially, this sounds monstrous and inhuman. But closer thought will reveal the superior humanism of such a market. For we must realize that there is a market for children now, but that since the government prohibits sale of children at a price, the parents may now only give their children away to a licensed adoption agency free of charge. This means that we now indeed have a child-market, but that the government enforces a maximum price control of zero, and restricts the market to a few privileged and therefore monopolistic agencies. The result has been a typical market where the price of the commodity is held by government far below the free-market price: an enormous “shortage” of the good. The demand for babies and children is usually far greater than the supply, and hence we see daily tragedies of adults denied the joys of adopting children by prying and tyrannical adoption agencies. In fact, we find a large unsatisfied demand by adults and couples for children, along with a large number of surplus and unwanted babies neglected or maltreated by their parents. Allowing a free market in children would eliminate this imbalance, and would allow for an allocation of babies and children away from parents who dislike or do not care for their children, and toward foster parents who deeply desire such children. Everyone involved: the natural parents, the children, and the foster parents purchasing the children, would be better off in this sort of society
(From: Murray Rothbard, “Ethics of Liberty”, chapter fourteen: children and rights)