It is coming - the great school supply sales. Every July and August, major big box and office supply stores offer phenomenal deals on school supplies. A little savvy shopping can save you a TON on the items that you and your children will need all year long. However, you can't just go into the stores and fill your cart with random stuff. You have to have a plan.
First, you need to gather your kids' required supplies list. Combine the lists to make one master list. Then, separate the items that are one-time costs (like things contributed to the classroom, or binders) from consumables (glue, pencils, folders, and paper). Then, you'll have to try to guesstimate how many of the consumables you'll need to get through the year. I like to add a little to items that we'll use for general arts and crafts around the house.
I like to make a spreadsheet, but I'm a spreadsheet girl. However it works best for you, as long as it works.
Once you have a solid shopping list, sort through the stuff you already have. I am always amazed at how many colored pencils and folders we already own. Cross those things off of your lists, or reduce the number that you need to buy.
I find it helpful to get some idea of what these items cost at full price, so wander down the office supply aisle next time you are Target, or check out prices on Amazon before you start the shopping season. You don't have to, but it does help.
Once your Sunday sales flyers start showing the back-to-school sales, keep an eye on prices. (If you don't get the paper, do a quick internet search on Sundays.) When you see a fabulous price on an item you need to buy, see if it works in your overall schedule to stop by that store. I don't recommend making special trips all over town just for school shopping; with the price of gas, you'd have to be getting some serious deals to make it worthwhile.
Once you find the right products at the right prices, it helps if you can do a little mental math to decide how much to purchase. If I think I need ten packs of notebook paper, how low does the price have to go before it makes sense for me to buy 20 packs, just in case? This is going to be a very personal decision, based upon your storage space, how many kids you have, whether you've got a move coming up, and whether you have an extra few dollars to buy those additional packages.
I have found that this worked really well when my kids were in elementary school. Now that everyone is in middle school or high school, shopping is a little less organized than I'd like. However, picking up the staples during the summer sales can still be a saving strategy.