A familiar part of debates about supererogatory actions concerns the role that cost should play. Two camps have emerged: one claiming that extreme cost is a necessary condition for when (and why) an action is supererogatory, while the other denies that it should be part of our definition of supererogation. In this paper, I propose an alternative position. I argue that it is comparative cost that is central to the supererogatory and that it is needed to explain a feature that all accounts agree is central to the very notion of supererogation: optionality. Perhaps because of this agreement on its importance, few attempts have been made to clarify and explain the notion of optionality. I argue that giving an account of the optionality of supererogatory requires drawing a line between doing the bare minimum permissible and going beyond the bare minimum and that this line ought to be drawn based on comparative cost of alternative permissible acts. Having outlined my account and motivated it, I discuss and reject two concerns that might be raised: firstly, that it is extreme cost, not comparative cost, that matters and, secondly, that in fact no cost is needed for an act to be supererogatory.