5. Purchasing unneeded items: You can often have items in your house, but not know exactly where they are located. Or you may have completely forgotten that you had already purchased something, since your closet or a cabinet is cluttered. Not knowing where items are located can result in you thinking you need something you already have -- and wasting money. 6. Return trips to the store: If you go shopping without a list and try to remember what you need as you walk down the store aisles, there's a good chance that you will accidentally forget something. If the item happens to be important, you are going to have to make another trip to the store -- wasting both the cost of gas and your time. 7. Rebates: There are a lot of opportunities to save money with rebate offers, but you have to actually follow through with the entire process. That means having your receipt, the rebate form, the proof of purchase seal and anything else you are required to submit sent in by a certain date. It's not difficult to do, but it does take a bit of organization. This can mean several hundred dollars saved off your purchase of computers and other electronics if you are organized enough to follow through. 8. Emergency purchases: Much like having to go and purchase a forgotten item, an emergency purchase is when you have to purchase something that you thought you had but don't -- or can't find. This can be at an odd hour when only over-priced convenience stores are open, meaning that you'll need to pay even more for being unorganized.