optical comms over the range you are talking about is much simpler,doesnt require licencing,is low power and can be directional or omindirectional.
I recently did something similar using an rs232<->irda physical level convertor, so although it didnt use the full irda stack it used the data compression to send relativly low speed data over a ten meter link.
Also RF is hugely expensive compared to optical,ive never found a good simple cheap rf solution.