It shouldn't be difficult for someone to come up with a meta-search service that would search for prices from multiple geographical locations, different user agents and (with lesser likelihood) different user profiles. Such a service would also have to provide the user the ability to use the lowest priced profile to complete the purchase (although this may not work for all websites).
Is there already something that fulfills at least the first two criteria across a range of products, services and sellers?
Is there already something that fulfills at least the first two criteria across a range of products, services and sellers?