Darn, that is a heartbreaker that the side plate doesn't match (in your original post, it was presented as all matching?) because, otherwise, it is a pretty nice gun judging by the photos (would like to have it in hand for a better assessment). With an original period magazine I still think $1400 isn't out of line for a unit marked gun in that condition ( the last character appears to be a "U", which would indicate that it was a Bavarian Ulan/mounted cavalry weapon...very desirable). JMO, for whatever that is worth.
If I was 20 years younger and still accumulating Lugers, I would give it serious consideration.
Ron