 In favour of payment, the main reason cited is increased supply, thus enabling recipients to have children that they wouldn’t otherwise have had—or, where scarcity per se is not an issue, giving recipients more choice. In addition, supporters of payment cite justice (gamete providers deserve to be rewarded) and autonomy (providers and recipients should be allowed to contract with each other as they see fit). Finally, pragmatic arguments are sometimes offered, such as the cost of prohibition or the possibility of its leading to an unregulated ‘black’ or ‘grey’ market in gametes. (Resnick 2001; Steinbock 2004; Wilkinson 2013)