I think it is a book but probably only contains the info you would find on wiki.  There are a few companies doing this (they must have a bot to create these automatically).  They troll through Wiki then put together some info and publish it as a book or e-book to sell.  Wiki allows this as long as the source is referenced.

They probably also have an Acaeum Wiki book as well.

It probably won't contain much of the modules themselves.  It will be basically a direct copy of what is on the Wiki pages.  Probably the Greyhawk page and then all the module pages pasted together with a generated table of contents.  Here are some of the Wiki pages:

http://en.wikipedia.org/wiki/Greyhawk

http://en.wikipedia.org/wiki/Against_the_Giants

http://en.wikipedia.org/wiki/Descent_in ... _the_Earth

http://en.wikipedia.org/wiki/Expedition ... rier_Peaks

http://en.wikipedia.org/wiki/Scourge_of_the_Slave_Lords

By the time you format these pages into book form (probably with large margins) - table of contents for each section, start each section on a new page, all of the references, etc you can probably get to 200+ pages quickly.

You may notice that their decision on contents is not the best choice.  They probably look for wiki pages that are linked and get the most hits and compile them into a book until it reaches a certain page count.  This "business" could easily be a couple man operation who have developed a program to generate all their books automatically.

I've run into this before where a student bought one and asked me about it thinking it would be a good reference for a course I'm teaching (that doesn't have a specific text).

I definitely don't understand the interest of this kind of books :/ and why some people could buy these books.
Perhaps only people who think that this is another thing...

And I am still very surprised by the price.

Probably why even the used copies are only $11.