5000$
100-1000 USD or so
You will need to contact Walther to find out.
Yes.
1961
http://www.p38forum.com/
Try posting at p38forum.com
Dieter Marschall's book on Walther has sn data in it.
250 or so
Try asking on the p38forum.com
about as much as your mother is to me!
Try the P38forum
Military P38s are dated from a 3 letter code, and not a serial number.