In-store radio is perhaps the lowest overhead delivery of information to the retail shelf. It would likely rely on FM microbroadcast and the very cheap and ubiquitous walkmans which can cost as little as five dollars, and of course provide access to everything else on the radio spectrum.
It also would not need to be installed in the store necessarily, but could be beamed into the store from outside without store participation or permission. Accordingly, it is one of the few technologies that would work well without friendly retail, but would simply work better with their help.
Disadvantage is that it would probably rely on a reading queue which would possibly have to combine several peoples' queries in the same list to read to them on one channel. However, if there is that much Consumerium Service access going on, then, probably, we are successful enough to deploy on more than one channel, or with other retail shelf or shopping cart or checkout counter methods.