If you blew all your money on your kids' back-to-school budget, here are three things you should be able to save some money on in September.

1. Mattresses. They're always a popular sale item for Labor Day, along with other furniture and appliances.

2. iPhones. Apple plans to announce their new iPhones on September 12th, so you should be able to score last year's models at a discount. They're about as good, but a year older so not as en vogue if you would.

3. Plane tickets. According to a study on holiday airfare, prices for plane tickets over Thanksgiving and Christmas will increase throughout October, November, and December. If you can book now, do it. September savings are a major reason to get on those holiday plans a bit early.

And a couple items you should hold off on buying are: TVs which will go on sale in November for Black Friday and January for Super Bowl, and Halloween costumes, which will get marked down the closer it gets to October 31st.