I’ve had my Kindle for five months now and in that time my spending on books has noticeably increased. The problem is that I can buy them whenever, wherever I want. And books that I’d think twice about buying in hardcover, I don’t even notice the cost digitally. There’s no question that it’s more convenient, but it’s definitely more expensive.

So I decided to investigate the many sources of free books. And by free, I don’t mean stolen—I mean library, public domain, or promotional copies. There are lots of different sources, but the whole thing can be confusing, with different file types accepted only on certain devices, and each source only listing their own few thousand books.

Amazon already lists a few sources: Project Gutenberg, ManyBooks.net, and Internet Archive. Goodreads also has a lot. Just make sure to download the files in the Mobipocket format (.prc) and move them into your Kindle’s Document folder. Project Gutenberg is my favorite. I remember reading The Awakening on Project Gutenberg during my first temp job in 1998. (Sorry, State Street!) Unfortunately, the stock is limited to books whose copyright has expired. It’s a great source of classics, but nothing new.

For that, you’ll have to go to the public library. Getting books from them is not a seamless experience, though. Even their Mobipocket-formatted books don’t work without some fiddling. Kindle Vixen suggests using the program Mobi2Kindle, but I couldn’t get that to work. Here’s what I did, which is a lot more convoluted. (And before you ask, yes Jason did help me out with this.)

Converting Mobipocket Files for Kindle (on a Mac)

The first time:

• Go to http://igorsk.blogspot.com/2007/12/mobipocket-books-on-kindle.html.
• Download Kindle Mobipocket tools. That downloads a folder named azw-0.

If your Kindle serial number starts with something other than B001 or B002:
In that folder, open kindlepid.py. Find the code:

elif serial.startswith(“B002″):
print “Kindle 2 serial number detected”

After that, add:

elif serial.startswith(“B003″):
print “Kindle 2 serial number detected”elif serial.startswith(“B004″):
print “Kindle DX serial number detected”

Save the file.

• Open Terminal (Applications, Utilities, Terminal).
• If the azw-0 folder is on your desktop, type “cd Desktop/azw-0/” and hit enter.
• Type “python kindlepid.py SERIAL#” (with your Kindle serial number in place of SERIAL#—it’s on the back of your Kindle) and hit enter.
• This should give you your Kindle PID; it should look like this: PDFZ4UF*GZ. Your local library will ask you for this number when you register your device there for the first time.

Each time you download a book:

• Download your library book to the azw-0 folder. If you’ve chosen the Mobipocket format, it should have the extension .prc.
• In the Terminal window, type “python kindlefix.py BOOKNAME.prc PID” (where BOOKNAME.prc is the name of your book file and PID is your PID) and hit enter.
• You should now have a book file with the extension .azw in your folder. Drag it to the Documents folder on your Kindle (or email it to your Kindle address). Ta-da!

This seems like a lot of work for a library book that will expire in 14 days. And most library books aren’t even in Mobipocket format—they’re in Adobe EPUB format, which I (and Jason) haven’t been able to figure out yet. It looks like in order to read them on the Kindle you have to strip the DRM. It’s a moral gray area that I’m comfortable with (they are library books, and it’s not like I’m selling them), but I haven’t even figured out how to do it yet. Maybe that’s another post. (Sorry, Lindsay!) Others are in .pdf format, and while it is possible to read them, it’s not possible to change the text size, which makes for a lot of squinting. The convenience alone makes it worth overspending on Amazon, don’t you think?

Too confusing? Did I leave something out? Let me know in the comments.