i dont think KBB is according to area either. when i was shopping for my wife's 3 series vert they were selling well above what kbb had them listed for. kbb also isnt updated frequently (yearly?). example, i was selling my Z71 during the gas crunch two years ago and kbb had it listed well above what the average listed price was.
i think $8k for a 10 year old cobra is pretty good, although a 93 would probably cost the same if not more. compare it to the price of GT and you'll see which one actually holds its value. heck, most cars from 98 arent worth shat now (compared to new price). when i was shopping for my cobra i was amazed at how well they were holding their resale value.