Consumerium checker

The Consumerium checker is a fictional scanner device that would be very cheap, very portable, and invisible so no one could really stop it from being taken into a store. It would receive the Consumerium buying signal without interfering with any spectrum used in or near the retail shelf, and it might even exploit a network of retail shelf devices (like price displays).

Its main capabilities are to swipe the barcode, map this into the Consumerium buying signal appropriate for that barcode, and display it. All within about one second.

It is probably on a ring you wear into the store.

Some best cases rely on such a device being available.