Please take a look and give me your thoughts

[saab-bob]

Hello tackkjr
Welcome to the forum!
Since the real experts haven't jumped in yet,I will try to give you some information.
You have a Mauser made late war P08 Luger chambered for 9mm ammunition. These are commonly referred to as "Black Widow" lugers and usually issued to German Army units.It looks all original. The grips and the magazine are the original style that where issued with the gun.The finish looks good with some honest wear.The magazine on these guns where not serial numbered,so if you want a spare one,any one of a similar type will be correct.
As for value,i would guess @ $2500.00.
If you want to get the correct holster, look for a late war black military style with the metal buckle.
Since your gun looks all original,there is a danger if you shoot it,a numbered part might break and decrease the guns value.
If it where me,I would clean and lubricate it really good and shoot it some. Use low power ammunition like winchester white box.
Your gun is the strongest of all the Lugers made up until the 1970's.
I take it your grandpa was on the German side during the war? So he liberated this pistol from the Russians! Nice.
Congratulations
Bob