I dunno, maybe. I have a black and something looks a little off to how her brothers looked at that age.
Some things to consider: he's 7 weeks old. Too early to be away from his mother and litter mates. They learn all kinds of things about dog hierarchy and social behavior from their mother and littermates at that age. Not having this time can cause problems later on.
Also, why does this guy want to sell him? Didn't he just buy him or has he had him for a week and decided it's not going to work out? Red flag and goes back to being taken from his litter too young.
If you like the puppy, take him, he sure is cute.
Oh and if you're thinking the white spot on the chest means he's not pure, black gsds often have a white blaze as babies. My Venus had like 5 white hairs at 8 weeks and they disappeared. One of her brothers had a blaze about that size and it's completely gone.
Venus of Crooked Creek 1/26/13
Otto von Hena-C 05/23/08
Morgan Donnermond 08/04/01 to 9/28/12 Long Live the Queen!
I have duct tape and I am not afraid to use it.