Flatbase is a responsive WordPress theme suitable for Knowledgebase or Wiki sites. Flatbase comes with built-in pages such as FAQ, Forum, KB and many more. It also supports bbPress for social engagement.
At ThemeForest you can buy and sell site templates and themes to skin popular CMS products like WordPress, Drupal and Joomla. Files are priced from just five dollars, based on the complhexity, quality and use of the file.