1300 for a WW2 PP is a bit high...
Here's some info about your PP.
It is a mid-war PP issued to the military. The Waffen marks indicate military proof, and as I recall, army/wehrmacht, other branches would be marked differently. This will command a slight premium over an unmarked "commercial" PP.
It does appear to be in decent shape, and from what I can tell in the pictures, not refinished. The safety does have some "blueish" color which I think is correct even for the duller finish guns.
Now, all WW2 Walthers have gone up, and this is has the proof marks, so it's a little more expensive, but I would try to offer a bit less, probably $1k is where I would feel more comfortable, but keep in mind that would be "retail".
You could go to Legacy Collectibles and search for sold guns to see prices, they are the experts AND I could be wrong.
Those marks on a PPK are rarer still, and the PPK would command a lot more $, but the PP is just not as desirable.
For reference, I own probably 10 to 15 WW2 PPs and 10 to 15 PPKs. Nothing "fancy" like the high end engraved ones that Legacy gets their hands on, but still, I know a bit about them.
James
PS If I can find the picture I have of serial number ranges, I can be specific as to when it was actually made. I think the 250,000 number range was in 43, but I'll see if I can confirm it.