Service providers of the future could dynamically negotiate for, and create their infrastructure on Grid based utility computing and communication providers. Such commercialisation of large scale gridsystems requires the provision of mechanisms to share the wide pool of Grid brokered resources such as computers, software, licences and peripherals amongst many users and organisations. Quickly and efficiently servicing resource requests is critical to the efficiency of such Grid based utility computing and communication providers. However, distributed resource negotiation is itself a contributor to lower system utilisation, as the negotiation process introduces latency and reservation uncertainty in the system. The CORA architecture is a market based resource negotiation system that utilises a Vickrey auction to make allocations of resource requests to resource providers. The architecture utilises a novel combination techniques to improve utilisation, including oversubscription, coalloc...