You download the sample from the iBookstore. You want to read the book, but you don't want to pay for it.There is a solution to that though. This post will tell you how to get Free iBooks.
Make sure you have the xSellize source. If you don't go to this post
1. Open Cydia
2. Tap "Sections"
3. Scroll all the way down until you get to "X Books"
4. Here is where a lot of iBooks are located. Just scroll and find the book you want to download
5. Once you downloaded the iBook, it will show up as an icon. Tap on it. It will open Safari.
6. Once Safari opens, tap "Open in iBooks"
7. It will open the book in iBooks. Then you can read your iBook.It works like any iBook.
8. Now you can start reading your new iBook
Note: Not all iBooks will be in the section, only a selection.