The switch was listed at about $60 (#53-508) in ClassicParts catalog from a year or so back. I don't know if Advanced Auto can get it or not.
You also may be able to get the steering wheel off by loosening the nut about 3 turns, then hitting the spokes from underneath with your hands. Be sure the nut is on far enough to keep the wheel from coming completely off and whacking you in the nose.
regards,
Leon
