What specific breed of dog costs $4k? I'm just curious.
Any breed, if you get it purebred from the "right" breeders can cost that much.
I don't know how much my brother spent on his purebred pointer, but it was definitely an unmustachian amount for "a dog". But he was specifically looking for a male and specifically looking at the lines, to the point that he had hunted with 5/6 of his dogs parents and grandparents before he made his decision. It is his hobby, so it definitely makes sense to me.
There are also certain situations where I can see that it would make sense to get a well-bred puppy from a breeder rather than rescuing. I/my parents when I was a kid have now rescued 4 dogs, and we got 1 from a breeder as well. 3 of the 4 rescues would be EXCELLENT with small children. 1 of them would not be, but you wouldn't have known it based on when you met him and based on the rescue organizations knowledge of him.
You are getting a mystery with a rescue dog. Certain breeds will do better than others, but you can eliminate a lot (
but not all) of the risk if you do your research and get a bred puppy. Of course, from what I've seen most do not do the research and most litters are not actually well bred, but I am certainly not eliminating getting a puppy from a breeder for my kids if the situation is right for it. Rescuing will be the preferred method, but it isn't the right way for every situation.
Similarly, my brother (the same who spent a lot on his dog) also fosters Pointers. I think they've had about 17 of them at this point. He'd tell you some stories, but the gist of it is that quite simply, rescuing and fostering isn't always as easy as the internet makes it out to be and sometimes getting a
well bred puppy is the better option. This is especially true for certain breeds, like pointers, where they're neurotic and high strung as a baseline. This is of course made worse by bad breeding and inbreeding, but he's written certain breeds off entirely due to that.