Headset -> Camcorder audio adapter

Does anyone know of an adapter (that won't set me back big bucks) to
be able to record what I hear in my headset onto the audio input of a
video camera? I'd like to do some narration with a little better audio
quality.

I've seen the cel phone adapters that are out there, and they're
nearly as expensive as a headset with the cel phone jack built-in.

I know a little about electronics, and figure the trick is to match
impedance. I get around 500 ohms on my headsets, and I figure that the
camcorder will need 8 ohms. That's about as far as I've been able to
get. Is anyone out there interested in purchasing one if I'm able to
come up with something?

I'd really like to just buy one, but haven't been able to find
anything on the net.

Thanks
DK