wireless garage alarm?

In article , tarquinlinbin writes

Yes, you can use equipment that works on the 458 MHz band which will go some miles with the correct aerials, but its not too cheap. Have a look at the RS online cat rswww.com there are some modules listed in there.

A Google search may throw up other suppliers. A look at the LPRA site may show more

I bought a wirless door bell from a local shed opened the switch and wired a magnetic reed switch in parallel with the contacts. Stuck the switch on the garage door frame and a magnet to the door (proximity switch) When the door opens the ding dong goes in the house. Works about