This paper presents a flow-based, auction-driven approach to resource allocation. This approach allows mobile stations to simultaneously negotiate for resources from competing providers. We use an auction at each provider to decide on the resource allocation, based on the offers made by agents representing mobile nodes. All agents in the system try to maximise their utility gained from the total allocation of resources. The focus of this paper is on the bidding strategy of a mobile station when faced with the opportunity to obtain network resources from multiple sources. We support the proposed bidding strategy by simulation experiments, which show that the resulting allocation is efficient under the limited scope of the simulation setup.We also show that multiple-access can increase the allocation efficiency compared to the situation in which agents have access to only one network.