Consider which items are non-negotiable like the class list of required supplies, says Kim Danger, frugal author and creator of mommysavers.com. Clothing, shoes, lunch boxes and backpacks allow for greater flexibility.

Past spending is a good starting point to this year's back-to-school savings. Look at last year's credit card statements and check registers to get an idea of what you spent on back-to-school shopping last season.

"By seeing what you spent in the past, you can challenge yourself to find better bargains this year," says Danger. "The exact budget will vary from family to family. You just need to spend within your means."

A good way to make sure you stay within your budget is to use the envelope system and put the cash you've allotted for each child into separate envelopes. Danger says cash easy to understand. Even younger kids get it that once the cash is gone, no more money can be spent.

Danger suggests using this opportunity to teach older kids how to budget by giving them a set clothing allowance so they can benefit from their own back-to-school savings.