Hidden Amazon profit: 3 book types most Amazon sellers don’t know are profitable

Here are three types of books it took me a long time to learn had more value than I realized…

Old math books. What? Am I wasting your time with mundane info like this? Hold on, let me explain…

There is one thing that separates math from nearly every other subject. And believe it or not, it never occurred to me until a thrift store volunteer, of all people, explained it to me. This is what she said:

Math is the only subject that is virtually timeless. An equation, algorithm, or theorem is as true today as it was in 200 BC. You can’t say this about nearly any other subject. There are advances in architecture, biology, and even archeology that renders books in these categories obsolete every few years. Not so with math.

Since getting this small dose of knowledge, I began to give attention to seemingly old and “obsolete” math books, and have been very surprised by the results. A hugely disproportionate amount of books on math have value.

Major qualifier: I am not referring to math textbooks. Textbooks become obsolete for reasons other than their content. Old textbooks are always low value, low demand.

Rule of thumb: If it’s on the subject of math, and you can’t easily pronounce one or more words in the title, it’s worth money.

Old books on university presses. You’ll see these fairly consistently, depending on where you source: Old hardcover books, often without dustjackets, without barcodes (often without ISBNs), published by “University of _____ Press.” These are generally on some super-obscure subject, and seem too old and weird to bother with.

Its very convenient to avoid anything without a barcode, and dismiss it as too old to still have value. Do that with nearly every category except university press titles.

Its even easier to dismiss a book without a dustjacket. I find myself subconsciously skipping over any hardcovers without a dustjacket (though I try to fight this.) But this is one book category where this assumption will cost you.

Two reasons old university press books hold their value:

• They are often the only books ever published on that particular subject. This is what university presses specialize in: Weird weird weird subjects that only a few hundred people in the whole world care about. Check the latest offerings from the University of Nebraska Press, for example. Any scholars of “naive american environmentalism” in the house? If you want a book on these subjects, you have to buy it from a university press. There is just no other option.
• The market is not flooded with copies. I have a friend who has published a half-dozen books on university presses, and he told me it’s completely average for a university press title to only sell only few hundred copies. Then they go out of print. And for the rest of human history, if anyone wants a copy, they have to buy yours on Amazon for $99.99 (that’s my general default price for old books for which I am the only seller.)

Packaging commonly found books as sets

I’m going to be vague on specifics here, but there are books series’ that are abundantly common anywhere there are used books, and have no value when sold individually. Yet I buy them anyway, because of one trick I learned: I can buy  them up, wait until I have a complete set, and then sell the set at a price much higher than the sum of its parts.

There are several series I do this with consistently – books that wouldn’t even net you 50 cents sold individually, yet will bring $25+ when sold as sets. As I covered in an article on my trick for making more money with books on eBay than Amazon, people are willing to pay you for doing their work. In this case, aggregating the books into a complete set.

Keep your eyes open, and you’ll start to see what I mean.