Once shtf, with in 3 days there will be nothing left on the shelves in shops. The big grocery stores will be completely out of food within hours. If there is power—lines will form and gas stations will be out of fuel quickly. The most obvious sources for certain items will already be picked through.
I am not by any means saying this is ethical but in a survival, total melt down situation this is great information to have in the back of your mind. This may just be the deciding factor of life or death for you or you family.
Photo Credit: LHOON / Flickr