Today I bought a set of bluetooth headphones from ASDA 20.
They dont state they work on the iphone but I thought I would try them, they are made fore ipod all models but when I go to the gym and use the docking stations on the machines they pop up with the message "not designed for this equipment" and asks to go to plane mode which basically means no calls can be made or recieved....and this is what happens when you plug the bluetooth adaptor in.
But the sound is fantastc and the range is too !
A bonus feature is the headphones can be linked seperatly with up to 8 other devices which was handy for my laptop bluetooth dongle...well worth 20

Sony DR-BT22ik