Its in excellent condition with box. Looks to be unfired.
I have no idea what it might be worth, but a question:
IIRC, back in the '70s Winchester sold a line of spring air rifles made in Germany. Was your pistol made in Germany?
There might be a niche for collectable air guns, but if it were mine I'd go ahead and shoot it.
Paul
That looks like a nice one, however it doesn't appear they sell for big $$. A search of Gunbroker shows a couple with boxes in the $140-200 area.
http://www.gunbroker.com/Auction/ViewItem.aspx?Item=531507411