First, let me welcome you to the LugerForums. It's good to have you here. Thanks for posting the pictures. Links are better for those who have a slow internet connection so don't feel too bad about it.
Tell your friend I'll give him double what he paid for the four guns, and I'll be getting a Hell of a deal! It has one matching mag, a matching serial number take down tool and a matching serial number holster? If it's for real and not a clever fake, it's worth quite a bit more money than he paid.
Actually, if it's completely fake it's worth quite a bit more money than he paid for it...
The S/42 was a wartime code for Mauser manufacture. The 1938, as you can imagine, was the year of manufacture and is a more rare year of S/42. I saw a similar one for sale with a non-matching mag, no spare, no holster or take down tool for $1600 recently.