Need a cheap voice control solution for my lights

For this project I wanted voice control lights in my room.
So I purchased a relay, put that in my light circuit, coded the arduino board to recieve serial commands from my pc and knocked up a C# program to send serial commands when it recognises certain words via my microphone and all was well.
Now obviously I don't want to leave my PC on 24/7 or have a USB cable going to the device, so my question is what can I do for voice recognition that is relatively low cost?
I know of the EasyVR shield but I'd be looking at £35!! I have a Raspberry Pi if that will come in handy?
Thanks
Harvey

Edit: spelling

You could make a version of The Clapper and count noise spikes....