Topic: Similar Device -- but $600!
On Make:, I spotted this device, which has the power to become a chumby with some software...
http://www.uniconsys.com/devkit-ucn2410-c.html
However, the pricepoint is 3x, not to mention that the chumby has a package and software.
However, maybe in the final production units, you could use their style of a Wifi module, rather than USB. It looks smaller, and since the antenna is separate, you could stick it on the other end of the chumbilical, where heat isn't as much of an issue.