Update:

> http://www.itjungle.com/tfh/tfh042814-story02.html [...]
> http://www.enterprisetech.com/2014/04/28/inside-google-tyan-power8-server-boards/

No price mentioned, but OpenPOWER members can now order the SP010 reference board from Tyan:

http://openpowerfoundation.org/blogs/blogpost1/