Embodiments relate to a marketplace for inter-network links between a balloon network and a terrestrial data network. An example method may involve a computer-based purchasing agent: (i) determining a demand for inter-network bandwidth between a balloon network and a terrestrial data network, (ii) determining one or more offers to provide an inter-network link, wherein the inter-network link provides inter-network bandwidth between the balloon network and the terrestrial data network, and wherein each offer is associated with a corresponding client device, (iii) based at least in part on a comparison of: (a) the demand for inter-network bandwidth and (b) the one or more offers to provide an inter-network link, selecting one or more of the offers to provide an inter-network link, and (iv) initiating a process to establish an inter-network link at each client device that corresponds to one of the one or more selected offers.