The Orange Pi is a new single-board computer out of China that costs just under US$10.
http://www.notebookcheck.net/Orange-Pi-is-a-US-10-single-board-computer-with-a-2G-modem.210624.0.html
So far Raspberry PI is the most open source hardware platform of everything there is now (to my knowledge), and still there are parts of Raspberry PI which are not documented. Every other Raspberry PI copy is just more close source, and therefore harder to work on. When I searched for something with better performance where I could freely install linux, then I couldn't find anything cheaper. Usually those competitors support only android, which is not very developement friendly