Does anyone know where in the Chicago area I can pick up what is commonly referred to as an "airplane adapter". You plug your personal headset into the adapter and then plug the adapter into the airplane's "entertainment system" socket on your airplane seat armrest. Then you can use your own headset instead of the filthly thing you can get on the airplane.

Several places sell it online (Radio Shack and several other places) but I don't have enough time to wait. Thanks!