Parents will be spending an average of $630.36 for back-to-school stuff for each their kids this year, according to the National Retail Federation. That's a lot of money, and some of these purchases are not even necessary.

Every year, kids and parents are pulled by trends and marketing pitches that only add up to the unnecessary expenses. As back-to-school shopping is a top priority this time of the month, here are some suggestions on what NOT to buy.

For younger kids:

1. Mechanical pencils and fancy pens, like gel or glitter pens. Kids often misplace regular pencils as it is. These types of writing tools are costlier to lose and are not required by teachers anyway.

2. Fall clothes and expensive, trendy clothes. Younger children will grow out of these during the course of the year, which means you will have to buy new sets of clothes come spring. You'll get more bang for buck with affordable clothes. Additionally, you can wait until after Labor Day for purchasing fall clothes, as it's still summer clearance at most stores around this time.

3. Expensive gadgets like iPads. If your elementary student is in need of a gadget, a less-expensive laptop will do. It will be more convenient for written compositions. Buying any gadgets at this point will be impractical as well. Better wait until October till December, when holiday season bargains are in full swing, according to CBS.

4. Bulky backpacks, backpacks with rollers. Bulky backpacks are unnecessary and unhealthy for children. They don't need to carry a lot of stuff for school when they can use their lockers for keeping some items. The American Academy of Pediatrics (AAP) recommends that kids must always pack light. As for roller backpacks, "Remember that rolling backpacks still must be carried up stairs, they may be difficult to roll in snow, and they may not fit in some lockers," said the AAP.

Some schools specifically require certain school supplies, so it may be best to wait until school starts before buying anything.

For college kids:

5. Expensive bedding. This will be stained or ripped in the long run, so better to be more practical with affordable sheets. Besides, college kids don't always change their bedding anyway, so it will be useless to buy them expensive sheets they will never use.