1. A method employing an electronic shelf labeling unit, mounted on a front of a store shelf, adjacent a store aisle, the unit having a front facing the aisle, and a rear facing retail items stocked on said shelf, the method comprising the acts: sensing image data from a retail item while the item is presented for sale on said shelf, using a rear-facing camera on the rear of said shelf labeling unit, said camera capturing said image data from a front surface of said item that faces the aisle; recognizing the retail item by decoding plural-bit data encoded in a machine-readable indicia printed on said retail item and depicted in the image data captured by the electronic shelf labeling unit; determining a price for the recognized retail item; and electronically presenting said price for said item using a display on the front of the shelf labeling unit, by reference to the sensed identifying information; wherein the method allows store personnel to move items on the shelf as-needed, and the electronic shelf labeling unit adapts automatically—displaying the price of a retail item that is within view of the rear-facing camera.