This PC is called CCM PC (Coupon Codes Mall PC) which is built in a Linux Powered PC. This Guide will give you all the information from online stores & their unique prices (note that the prices were written when this guide was made but you may be can find it with a better price because online stores always are giving promotions with the PC Pieces products).
By getting this CCM PC you are not getting the best PC in the market. It is very basic and does not include keyboard, mouse, monitor or a copy of windows because it is based on Linux operating system which is free (open source). But if you are curious on how a computer works, there is a immense satisfaction in building your own design too. It is a great starter project, and the beauty is that you can customise it as much as you want and your wallet allows.
http://www.linuxlinks.com/portal/news/article.php?story=20090309134420766