Basic microcontroller + RF transmitter/receiver plausibility
They make a msp430 with a built in rf transceiver. They call them the CC430. There are many others. All that you've said you want to do is possible ;)

Also their EZ-RF kit is pretty easy to use and fun to play around with:


I think I got all mine free but it looks like they're only $49.  There are bunch of other guys like microchip who make micros + RF solutions.