Fair price for whom?
Pricing for lugers is highly variable, as is the actually selling price; depends on where, when,
how, to whom, and by whom it is sold.
That is a nice looking luger, highest "price" is likely off the table as it is a "police" modified luger;
the non-original mag hurts also; but it is a scarce one for a collector of "police" lugers.
Price range could be $1500 to $2500; and everyone who posts will have their own opinion!
JMHO.
In the 2018 "Blue" book, the price for a chamber dated S/42 in 98% condition is
$2550, and "with Navy/Police" markings $4500- an estimate that is "nuts" IMO; but for sure a Navy would sell for more than a unmarked or Police pistol.
One would deduct from these for the mag- but how much who knows?
The "Book" would be great for selling, but a curse for a buyer.
Again all just "opinion", and we all have one.