Rat Shack:
VOX headset on clearance for $4.97 (catalog # 21-1831)
VOX adaptor for most aftermarket microphones/headsets $2.97 (21-1832)

WalMart:
Hands free headset w/a bunch of priceless little adaptors for just about any
application you can think of (FRS, ham, commercial radio, cell phones, etc.)
clearance $5.00
(UPC 026616602414) Southwestern Bell product # S60241