I have a number of boards for sale. These are completely tested and new.
Please visit this site: http://www.mazelea.com
The small one measures 3x4 centimeters, and includes all the functionality and I/O, other than the Ethernet.
The boards also include special parallel port JTag included, but you would need parallel port on the PC to run it.
Regarding RF, these are not really RF, the onboard frequency is around 18 Mhz, but it is possible to interface RF chips, for example matching single chip Zigbee modules, these should be built according to the 2.4 Mhz spec. for these types modules and interfaced over the SPI, so all that needs to get done is attach the SPI lines from such a module to the already prepared modules you see at this website, or redesign the original boards with the Zigbee chip onboard, and then run and compile the appropriate software.
If you need more data and the prices, E-Mail me at firstname.lastname@example.org