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For online shoppers, and everyone else for that matter, Amazon needs no introduction. They’re fast, they’re reliable, and their prices are known for being lower than the majority of their competition.

But not everything should be purchased on Amazon. You know how it goes: You’ll find a few deals on Amazon, start getting excited and looking around for more deals, and before you know it you’re buying everything you can on the retail giant’s website.

If you don’t know what to look for, you may not even realize you’re overpaying for items unnecessarily.

Look, Amazon is a great place to shop, but one of the keys to saving money on Amazon is knowing which items are smart to buy (items they tend to have the best price on) and which items you’re better off getting locally or elsewhere online.

Not to mention you can skip those items on your regular shopping trips, which saves you time and hassle.

So whether you’re an Amazon fanatic or just a casual shopper, here are 7 items you’re sure to save money on by purchasing from Amazon.

Books

Amazon started out as an online bookstore, so it’s no surprise they’re prices are consistently competitive. They also have a massive selection compared to traditional book stores, which makes shopping for books elsewhere senseless.

Here’s a quick price comparison of a popular book “Born to Run” by Bruce Springsteen:

Amazon: $19.50

Barnes & Noble: $20.28

iPhone Cases

iPhone cases can get expensive if you buy them through a mobile phone company like Verizon or T-Mobile, or if you buy higher-end cases through companies like Sena.

However, if you’re simply looking for a quality (and somewhat stylish) iPhone case that will accomplish the job of protecting your phone, Amazon is the place to go. Even if you’re looking for more popular brands like OtterBox, Amazon is still going to be one of the cheapest – if not the cheapest – place to buy an iPhone case.

OtterBox Commuter Series iPhone 6/6s case price comparison:

Amazon: $16.80

OtterBox Website: $39.90

Diapers

We’ve talked about this in a previous article, but one way to save money on diapers is to buy them through Amazon or sign up for a diaper subscription through Amazon. After all, you’re going to have to buy them anyways, so you might as well go ahead and pay a set amount to have them delivered to your door for you. You’ll save yourself time and money.

But even if you don’t go the subscription route, Amazon can still save you money on diapers.

Pampers Swaddlers Diapers Size 1 (8–14 lb) Economy Pack Plus, 216 Count price comparison:

Amazon: $37.97

Walmart: $39.97

Light Bulbs

Light bulbs are another item that you simply can’t avoid purchasing. As long as you have lights, you’ll need light bulbs, so why not purchase them on Amazon and have them delivered to you for less than you can pick them up at the store.

GE 60 watt bulb 4 pack price comparison:

Amazon: $6.16 per 4 pack, comes with 3 4-packs

Walmart: $6.18

*Amazon has even better prices on other bulbs that Walmart doesn’t show in their online system, so all-in-all I think you’ll find you get a better selection and slightly better prices buying light bulbs on Amazon.

K-Cups

If you have a Keurig, then you know just how convenient K-Cups are. The only problem is, they’re crazy expensive! Don’t worry though, because Amazon has you covered, so you can enjoy your quick, easy, tasty coffee without the guilt trip of spending too much money.

Green Mountain K-Cup price comparison:

Amazon: $39.59 for 72 count

Walmart: $9.98 for 18 count

Prices on more popular name brand K-Cups tend to be very similar, but you can save a decent amount of money by purchasing the larger packs of K-Cups from lesser-known brands on Amazon.

Personal Hygiene Items

Tired of spending an arm and a leg on personal hygiene items at the supermarket? Why not buy them on Amazon and save the space in your shopping cart. You’ll save money by doing so.

Crest Whitestrips price comparison:

Amazon: $36.90

Walmart: $37.45

Cleaning Products

Cleaning products eating away at your grocery budget? It’s time to start using Amazon to save even more money at the store, and even more buggy space. (You might even be able to make the express checkout by now!)

Clorox Disinfecting Wipes Value Pack, 225 Count price comparison:

Amazon: $8.54 with Subscribe & Save

Walmart: $8.97 (normally $9.97)