I do think it's a great idea to shop in bulk to save $, take advantage of the buy one / get one or two free sales etc. for anything that will store without refrigeration.
Living in New England, I don't see a need to store water since we have so many streams, ponds, lakes everywhere and I can just filter.
When the talk turns to the roving gangs with guns coming for your food scenarios, I just tend to think of heading for the woods rather than making a stand somewhere. Won't find me anywhere near a city if that ever happens. I'll be in the middle of nowhere with a good rifle, ignoring the hunting seasons :-)
My basic bug out items? Comfortable pack, synthetic sleeping bag, sil-nylon or plastic tarp, wind pants and jacket, fleece, winter hat, wicking layer top & bottom, 2 lighters, little ziploc with a handful of firestarters (I'm lazy), water filter, pocketknife, string, small first aid kit, bug dope, water bottle, led headlamp. Good boots and couple pairs of socks.
Not so basic - add hennessey hammock, sierra zip stove, solar AA charger, sleeping pad & chair kit, food and spices, reading material, toiletry kit, sewing kit, bandanas, sunglasses, sven saw, micro gps, and coffee.