On books and electronics by going onto www.amazon.com for old or used items. I saved money last semester purchasing used books on Amazon. You can buy a lot of used books in good condition, its just a matter of choosing the item carefully after reading descriptions.
I bought two chargers for a very old i-pod model on Amazon for close to nothing. Both chargers work beautifully, and would have cost a lot more if I bought them in a store. I also bought a charger for my Mac book which works.