Current pricing mechanisms for end-to-end Internet transport involve heavyweight service-level agreements (SLAs) between providers, which are enforced through policy configurations in the Border Gateway Protocol. One drawback of this practice is that BGP gives preference to a single path, and thus inherently limits the richness of the network topology available to users at any time. Moreover, the coarse granularity and long time scales of interdomain SLAs limit the effect of competition and market forces. In this paper, we show how the use of software-defined infrastructure, in the form of an Economic Software-Defined Exchange Point (ESDX), can help enable a more dynamic interdomain ecosystem. In particular, providers can use the ESDX to establish short-term contracts and thus access a much richer set of path alternatives and contracts. We show that transparent pricing mechanisms are possible and that a pricing network equilibrium can be achieved.