Hi Tony,
I have provided your nephew Chris with some info. over on Jan Still's GunBoards.
Rather than repeat those posting, I have provided a link to that other discussion :
http://luger.gunboards.com/topic.asp?TOPIC_ID=11080
Also...you and your family might consider a professional appraisal from the Simpsons LTD shop. It costs $ 135 plus S/I both ways...but might give you another opinion regarding price to balance out against some possible "low-ball" offers that will certainly come your way as well :
http://www.simpsonltd.com/luger_appraisal.php