WPeBooks was created and launched by Ron and Andrea Rennick in September of 2010 as a place for the couple to make and sell ebooks, plugins, and resources for WordPress Multisite users. Starting January 15th, this coming Saturday, all reports are that WPeBooks prices will be increasing across the board.
WPeBooks currently hosts five Multisite books at around $25 each. The books typically come with a plugin and additional support, if needed. Andrea Rennick also said that the two are hard at work updating all of their books and resources for WordPress 3.1, in preparation for the upcoming release.