I was helping a guy out the other day with a topic like this one, he was making a R/C robot on the cheap. He found some encoder/decoder chips that provide 8 inputs/outputs (encoder/decoder). You plug one of those into a RF transmitter module ($8) and voila! 8 transmitted on or off signals, with no microcontroller!
That website ArcMan linked to sells a whole pack
, providing 8 bits (8 on/off signals) of transmitted data. The pack has the encoder, decoder, transmitter, receiver and 2 antennas. just plug it in, and away you go!
This is the easiest solution i can think of without designing a transmitter yourself, and the aforementioned pack is only $25
PS. If you only need 4 signals, then buy the 4-bit pack