How about I take some baking foil, cut out a 6" square and put a small hole in the middle.

Then I place this square against my ear and hey-presto I've shielded my head from naughty radio waves blasting into my head from my evil phone?

If you're interested, I'll sell you it for £9.99. Now I can't say fairer than that can I?

Rubber bands to hold my 'device' against your head will cost you extra though..