What goods would you like to offer? I think it's a great idea, just thought yesterday about how one day supermarkets could handle cryptocurrencies.
I guess you won't be able to make traditional fix prices with paper labels on the shelves though
You will need monitors that always show the "live" price adapted to current exchange rates.
Paying could work (like in some of the ATMs) with QR-Codes and mobile phone apps.
PS: Finally writing my first post here, I built a rig one month ago and am interested in the whole bitcoin-thing since 2012