Very inexpensive 2 channel RF transmitter & receiver!
I found this site a while back and ordered the kit. It works great! I thought it might be of interest to some of you guys for a wireless rangefinder or jet pack smoke or... well whatever 12 volt dealio you may want to actuate!
315Mhz remote relay switch kits - 2 channels [WLS103B5B] - $19.50 : Seeed Studio Bazaar, Boost ideas, extend the reach
Check out the rest of the site too, they have all kinds of stuff that might be useful. The only catch looks like you are ordering directly from China, (slow shipping). Mine took 2 weeks to get here.