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If your child has some required reading from their school, or just wish to read for fun, you'll want to know where to buy cheap new and used books online so that you can get the title you need. Fortunately, you've got tons of choice beyond Amazon and major book stores. I've shopped at all of the stores that I mention below and can attest that they are reliable and legitimate. I'll separate out the stores according to whether they're for new books or used books.
New vs used books
Used books can be better for the environment, and usually cheaper too. But new books help support the author who wrote the books, plus you can be absolutely certain of no damage to the books. It's up to you what to get. Occasionally you'll have no choice: if your child wants a book that's been published within the last couple of years, odds are that there are not many used copies around just yet, and even if you find a used one, there's not going to be much price difference between that and a new one.
I'll go ahead and start with used book stores, because that's my usual go-to when shopping for our family's books, and then move on to the best places for new books.
Please be aware that some of these stores may still be experiencing shipping delays due to the pandemic, compared to during normal times. To help with that, I'll indicate where there are little to no delays, based on my recent experience buying my children's summer reading books.
Best places to buy used books online
My absolute favorite place to buy used books online is BetterWorldBooks.com. This is because they have a socially conscious mission of improving literacy in underprivileged areas of the world, and an environmentally conscious mission of preventing books from going to landfills. For every book you purchase from them, they donate a book to literacy programs in areas of the world where books are rare. It even keeps track of that number for you - to see what I mean, take a look at the screenshot of my account below. And their prices are really cheap. The icing on the cake is that every order has free shipping worldwide, and you have the option to pay a little extra to make the shipping be carbon-neutral. For US orders this works out to be typically less than $1 extra for an order of several books. All of these features combined is why it's my go-to place for used books.
BetterWorldBooks.com has a very large inventory and because of this, you can expect that most children's titles which would be on a typical school reading list should be available there. They are very reliable. Delivery is through the postal service, at least within the US, so it's a lot more environmentally conscious than having a courier truck do the delivery.
At the time of writing, for US deliveries, there are little to no delays; orders are fulfilled within business 2 days and then the additional time is however long it would take the postal service currently to deliver.
eBay is my second favorite place to buy used books online.
Because individual people are doing the selling on the eBay marketplace (not one big company) there are pros and cons. It's individual mom-and-pop stores selling items, so it's shipped as quickly as that person can get your item to the post office. They're not affected by warehouse issues from the pandemic, or things like that. On the other hand, reliability can vary from seller to seller. If you buy from eBay, check the seller's feedback rating first. I personally would not buy from anyone with a rating of less than 99.0%, but your cutoff is up to you.
I've had no delays for items that I've purchased from eBay sellers within the US, but shipping is delayed from overseas sellers because of longer than usual international shipping transit times. So in the item listing, check where it's coming from before buying. I have not ordered from overseas sellers recently because of that issue. To make your life easier, you can apply search limits: both on mobile and on desktop you have the option to limit your search results to your country.
Used books on Amazon
Many people don't realize that used books come from individual seller locations and not Amazon warehouses when you buy used on Amazon. So you'll get an experience that's closer to eBay when you buy a used book on Amazon. If you've never bought used on Amazon, it's quite easy. I'll illustrate it on a computer but it's the same general process on mobile. First you find the book title that you want, and it will show you the prices for the new item. As an example, I'll pretend I want to buy Tales of a Fourth Grade Nothing by Judy Blume - the link will take you directly to the listing on Amazon, and at this point your screen should like like the one below. Then click on "...used from $...." under the paperback edition as shown below.
They have the link in teeny-tiny writing so it's easy to miss if you don't know. Anyway, once you click on the bit that I've circled, you'll get a list of each of the pre-owned copies that are available for purchase, then you can pick the one you want and proceed as you normally would with Amazon checkout.
I'll be frank though that this is not my favorite place for used books. This is because the price plus shipping is often quite high.
It looks like you're getting a good deal, but by the time you add the seller's shipping cost, it can cost a similar amount or even more than ordering it new. This is because Amazon charges relatively high fees for people to sell on their platform (compared to eBay for example), which means that Amazon sellers then wind up passing along those charges to you with higher prices or higher shipping costs. Pre-owned books on Amazon are generally not Prime-eligible, so even if you have a Prime membership it won't help you there.
OK, that concludes the used books. Let's move onto new books.
Best places for new books online
Although it might seem surprising at first glance, Target has an extremely good inventory of new books online. The reason it's not the first place you would think of is because when you shop in store, you won't see a ton of titles. Well, it's a completely different story when you shop Target online - they have a lot of books. Prices are very reasonable and can often be even cheaper than on Amazon.
At Target you will need to meet minimum order amounts if you want to get free shipping, otherwise you'll have to pay shipping costs. This is similar to many of the other big-box retailers, and as an added bonus, Target is very fast at shipping. I've ordered some titles there recently that I couldn't find at used book stores, and they arrived really fast. So this is my favorite go-to place to buy new books. Plus, the free shipping order minimum at Target is not a big issue because I can buy other household items that I would normally buy there anyway as part of the order.
If you love free shipping and hate minimum order requirements, then Book Depository is the place for you for new books. Book Depository was bought by Amazon awhile back, but it operates separately. Book Depository ships worldwide - I've bought books and had them shipped everywhere: to my house, directly to my niece's address in New Zealand, to my mom's, and more. Even one book will ship free worldwide. Pricing is nice and low, and it's very reliable; I've shopped there for years. With so much going for it, you must be wondering what the catch is. Yes, there's a catch: it's by far the slowest of all options (used or new) in this article. Even in normal times, shipping took a long time (around 3 weeks for me). These days it's likely to be even slower. It'll get there, it just takes awhile.
So the bottom line is that Book Depository is a good option if you are not in a rush for the book. For example if you're buying something for yourself to read whenever, then that's a great place from which to buy. But if you need it quickly, go with a different store.
Walmart has a similar situation to Target going for books, but the downside is that the Walmart range of titles isn't quite as big as Target's. If you shop anyway for household supplies at Walmart and want to add books to your order then this is the perfect option for you. If you're looking for a well-known title then Walmart will have it, but otherwise you might need to look elsewhere.
Of course, Amazon is one of the best-known online book sellers for new books, and their listings will show you the new version of the book by default. They also have the advantage of doing an excellent job at showing you other books you'll like based on one book. So for example, if your child likes and already owns the popular Lightning Thief series by Rick Riordan (the link will take you to the listing, if you're curious) then you just scroll down the page and it'll show you similar books that you'll like.
So Amazon is the best option for online browsing because it'll predict pretty accurately some other titles you'll like based on viewing one title that you know you like. Amazon also has the "look inside" feature, which is great when you're looking for books for your kids, since it'll show you a few pages and it allows you to get a feel for the vocabulary and style to see if it's at your child's level.
While Amazon certainly has a lot going for it, the downside is that unless you have Prime, shipping times can vary a lot. It can seem random how quickly or slowly you'll get it. Plus, making orders up to free shipping can be frustrating since some other categories of items (e.g. school supplies) can be pricey compared to buying that type of item elsewhere. If you're in my situation and don't have Prime, then I'd recommend buying your books and other items at Target instead of Amazon.
You have plenty of options when it comes to buying books online. For used books, I recommend BetterWorldBooks.com, eBay, or Amazon. For new books, I recommend Target, Book Depository, Walmart, and Amazon.