Index Cards
If you are a parent, you probably know that school kids can finish a pack of index cards quickly when the exam season is here. A pack of hundred cards only costs 50 cents if you go to the dollar store. If you prefer to buy in bulk, you can also get 12 packs for $6.
Flashlight
While it is not of the highest quality, you will find mini flashlights useful when the power goes out. They have a keychain hook as well, so you can carry them around with you! They are cheap so might as well.