About how much is a 1942 German luger in good condition worth?

There are dozens of variations of the Luger pistol. Without a LOT more information, I can only say between $400 and $1200 dollars. Value will also heavily depend on exact condition and originality. Please do NOT attempt to "clean up" a collector's firearm- that can destroy much of the value. You should find a dealer or collector that is experienced with Lugers for a first hand evaluation.