For some items, you can scope out the stores before hand on Wednesday to see where they are stocked. Not for big ticket items, but it helps for things like jump drives, blank cds, dvds, etc.
Also, bring bottled water or something to keep you hydrated, maybe snack bars for energy. If When going to a lot of stores, and spending a lot of time "in the BF rush", I don't like to take time out to get food or drinks, so having hot caffinated beverages in a thermos, bottled water, and energy bars really helps keep me going.