Wireless headphones may be coming down in price but they're still unnecessarily dear. I'm not in desperate need of them now my headphones have a two metre wire, but I still walk off from time to time with them on and end up tugging a tangle of wires out.
I bought an FM radio for £1. Not just that, but I didn't pay for it, someone else did and decided they didn't need it. The parts for it must've cost less than 10p.
The wireless transmitter was a little harder to come by as they're not so common, but people tend to use them in cars to connect their MP3 players to the car stereo and so on. I got my paws on a partly broken one, but it gets the job done.
It would be nice to find out if it's possible to turn a receiver into a transmitter easily, as receivers are around twenty times cheaper. I, however, couldn't be bothered.
And that's about it - transmitter into PC, receiver in your pocket. The next thing to do is to build them into a single unit with a charging dock and everything, but even without it works decent enough. So there we go, that's a few bob there I've saved.