My experience suggests the following items are likely to be popular(based on typical disasters, rather than long-term TEOTWAWKI scenarios):

1 Tobacco/lighters
2 alcohol
3 Toilet paper and disposable diapers
4 Feminine hygiene products
5 Plastic trash bags
6 paper goods-paper towels, plates, plastic utensils, cups, etc.
7 Bleach and general cleaning supplies, like brooms, mops, buckets and cleaning agents, especially Lysol brand spray
8 Batteries in common sizes
9 gasoline, rather than diesel
10 Plastic tarps, duct tape, and temporary repair/salvage supplies
11 Propane, Coleman fuel, charcoal briquettes
12 Borrowed use of satellite phones and internet access

Jeff