WTB/ISO Dura ace 7700/7800 Short cage rear derailleur

Looking for a replacement rear derailleur after cx season broke my derailleur. 7700 or 7800 short cage model preferred. Scratches ok, so long as it isnt bent or crooked in any way. Budget $30-50 depending upon condition. Budget reflects wife's input as well as recent ebay listing comps. Contact off list with what you have available. Thanks.