1. A computer-implemented method for virtual resource cost tracking, comprising: under control of one or more computer systems configured with executable instructions, maintaining, at a virtual resource provider having a plurality of customers, a virtual resource implemented by a set of implementation resources including at least one implementation resource capable of being allocated as a plurality of implementation resource allocation units to a plurality of virtual resources associated with the plurality of customers, said at least one implementation resource dedicated to virtual resources of a set of customers of the plurality of customers; determining an active resource utilization amount corresponding to at least a first implementation resource allocation unit of said at least one implementation resource that is allocated to implementing the virtual resource; determining an inactive resource utilization amount corresponding to at least a second implementation resource allocation unit of said at least one implementation resource that is unallocated due at least in part to being dedicated to virtual resources of the set of customers; determining at least one cost of the virtual resource based at least in part on the active resource utilization amount and the inactive resource utilization amount; and providing a presentation of said at least one cost of the virtual resource to the set of customers.