I use el-cheapo Hope RFM83 / 85 radio links
@Boffin1 - Where can you purchase these? I can't seam to find anything through google other than the specs for them.
I'm interested in trying these but I notice in Nick Gammon's article about a radio-controlled car based on these that the receiver's data pin couldn't drive the Arduino input pin directly and had to be connected via an op-amp. Do you have the same problem?