I recommend buying only name brand items because they are of better quality and are more likely to last. However, when in a bind or if you have low funds you can always check a dollar store.

• baking soda (has many uses other than food related - burns, cleaning, deorderizing, etc.)
• bandaids
• batteries (store in ammunition containers)
• candles
• cleaning supplies
• dental hygiene items
• flashlights
• hand sanitizers
• kitchen wraps (tinfoil, zip locks, plastic wrap, etc.)
• lightbulbs
• matches, lighters, or other fire starters
• medications
• paper towels or cloths
• peroxide
• plastic sheets (to make a contamination room, create shelter, use for keeping messes contained, etc.)
• rubbing alcohol
• small plastic containers with flat lids for stacking and organizing small items
• toilet paper
• wet wipes (maybe - they dry out eventually)