Even without an API it should be possible, in theory, to just parse the data directly from their websites.

This also gives the grocery stores less of a leg to stand on in terms of legal or practical recourse. They chose to create a publicly browsable database of their prices; all you're doing is browsing it.

Huh. Now you've got me wondering... Could you leave a device hidden in store that receives the IR signals that program the tags, capture that information, then parse it out later? You could literally log prices changes at the shelves, in real time.