Hi,
You can probably Google and find out alternative cheaper RF products if any exists, since I think this band of HF is being promoted as licence free band by others also. Atmel also may have an RF product for such applications? If the distance is only 50 meters and if wired solution is acceptable, you can use either RS485 or simple FSK modems to send data across. You can also send FSK or DTMF data over a telephne line for such applications.
Regards,
Laktronics