Used Book Market

Got a book in the mail yesterday from Murfbooks. I ordered it on Amazon about a week ago. The price was a penny, shipping was $3.99. The packing slip that came with the book identified the seller with a 13 digit number. The order number had 17 digits. Then there was this line:

aisle 13 Bay 6   Shelf 1    Item 909

This must be a really big operation. Just from looking over the listings on Amazon there must be a couple of dozen of these places in operation in the USA, maybe as many as one in each state. They obviously aren't making any money on the sales price, so they must be making it in the shipping. Looking for more information, I came across this discussion on Reddit. I've excerpted the relevant bits:

11 Oct 2014
I managed an online book company for the past 4 years. It's the shipping. Amazon sets the shipping charge for all books and media at 3.99 (USD). Most of those books are going to cost me around .80 (possibly less) to ship anywhere in the US, .08 for materials, labor is pretty small, on the order of fractions of a cent for any one book. We list around 1200 books a day, and ship around 2000-2500 a week. Pretty much, it's volume (which also gets you the shipping discounts for being a bulk mailer), and cheap shipping. - Alfowick
Where do you get the books and how much do they typically cost? - jraby3
Everywhere. We take donations, we work with recycling companies, bookstores that shutdown, old stock from thrift stores, libraries. Cost is going to vary widely with the quality and "status" of the books. Big cost difference in buying stuff that has been sitting in a thrift store, versus nice remainders or overstocks from a clearinghouse, but say around .18 per pound. We buy in bulk so we do this for about 40,000 lbs at a time, once a week. Around 70 percent of that (in a really good load) is worthless and will be recycled, donated, or sold in our brick and mortar store. We don't throw books away. We have been moving away from buying books outright and do a lot of consignment work now.- Alfowick

P.S. The book is With Charity Toward None: A Fond Look at Misanthropy Hardcover by Florence King. Don't know anything about it, but Tam recommended Florence, so I thought I'd give her a shot.

P.P.S. I bought the book for a penny, plus shipping, but now the lowest price is $3.88. I guess dying is one way to boost your popularity.