1920 DWM Luger

[VincentL]

Hi,
my neighbour offered me this luger that was previously his fathers.

It's a 1920 DWM with all matching numbers (592 if I remember correctly). two magazines with out numbers and a holster with tools inside( what's up with this 28? it is not the serial of this weapon, any chance it doesn't belong to this gun?).
The inside of the bore shows signs of wear, and very very little pecks of rust (weapon was last used in 1944)

I'm not quite sure how to price this weapon and I want to offer my neigbour a fair price. so what is your advice?

Vincent