Any electronic hobby kit junkie out there ? How do I create a wireless countdownt timer below $100 prototype ?

Question

Push button is pressed , countdown timer on LED panel starts with audible number count speaker. Can I get both the speaker & the LED timer display panel linked from the push button by wireless technology ? Distance of 20metres from each other. I know Sim Lim & Rochor Centre sells the ready made hobby kit but they are all wired. Can anybody advice on how I can get it to be wireless yet wont blow my budget? Im working on a WITS project below SD$100. Thanks :)
PS: Bluetooth, Radio or Infra red ????

Answer 1

Well you say that you can already find the ready made wired version so all you have to do is make that wireless, which should be an easy task. I wouldn't use IR if it's going to be used outside, i.e. for model rocket launches or something as the bright ambient light and the sun would do a good job of blocking your remote signal. Bluetooth is more complicated than what you need. You only need to send a single push button signal. Radio is the way to go. Here's an example of a unit that'd do the trick:
http://www.electronickits.com/remote_control/rf2.htm

It's $30, but I'm sure you could do it cheaper by going to your local thrift/second hand store and finding an R/C car, ripping the receiver and servo out of it and using that to trigger a switch with the remote.