Errr last time I looked England ,the states ,Australia ,SouthAfrica and other Commonwealth countries and many more countries have public frequencies on which you can transmit without any licence .
Yes they do but you are not permitted to build one of these yourself, you can only operate "type approved" transmitters in these frequency bands.
A number of vendors on EBAY have small 900MHz keyfob remotes that offer 4 channel output and are network addressed, the latter meaning the reciever only responds to transmissions matching its site and unit address. They are range limited to 100 feet. I have 1/2 dozen of them I bought for possible use as shutter release on an airborne camera platform without tying up flight controls.
I did the hard part for you, I looked it up..
http://www.ebay.com/itm/Portable-4-key-Wireless-Remote-Control-Transmitter-w-Receiver-Module-Board-/200683881664?pt=LH_DefaultDomain_0&hash=item2eb9b104c0
@tytower
You forgot to mention Canada... XD
@drippygarry
I kook at this system at HVW ---> http://www.hvwtech.com/products_view.asp?ProductID=540
It might work. It look like a car remote - to lock the doors / activate the alarm system. And it's FCC / Industry Canada approved.
Thar ya go mate! 2 supplies of the very same thing, right down to the decoder ic's. On a side note the RX board has a pilot output pin that pulses on the incoming data upstream of the decoder.
Sorry, I did not look at that link.
Here's an addition to what everyone else has just suggested on eBay . It's the key fob and receiver module along with 4 relays $7. You can't really go wrong!
Or even remote control sockets £7?
The RF modules you can pick up cheaply are great and with the VirtualWire library, I had a system transmitting a temperature within minutes!