I have a guy wanting to trade me a marlin 336 30-30.  I dont think it is worth as much as he does, so I wanted to get some opinions.  The serial number prefix is 17xxx, that should make it a true Marlin manufacured in 1983, correct?  I would rate its condition in good, but not very good.   It has typical handling wear and marks, but still funtions 100%.  It has some type of peep sight on the rear.  Just a rough estimate, how much is it worth?