Ok, something has to create that pattern, and recognize it on the other end to be ready to act on the real signal.
Something like a Mini-uino could do that for you.
$2 for a board (I have 50 boards arriving from iteadstudio any day now, 37 are spoken for),
resistor, couple of caps, crystal, ~50-60 cents total?
$3.83 for uC, http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=ATMEGA328-AU-ND
3 AA battery pack and some programming for virtualwire to send a message, you're on your way ...
Or thruhole parts board to do the samehttp://store.nkcelectronics.com/arduino-runtime-board-rev-b.html
Need AVR ISP, or Arduino set up like one, to install a bootloader, then can download programs via serial interface.