First, you cannot nor should take a pup home at 6 weeks! If your breeder is doing this, run away, s/he isn't very thorough nor following established guidelines.
Second, beware "Papers and lineage". It takes nothing (and means even less) to get "Papers" thru registration with AKC, and every dog has "Lineage". It's the dogs on that actual lineage that matter, take a look and go online and search their pedigrees and performance history. You'd do well to make sure the parents are OFA acceptable, and that the pups have been medically checked and cleared, dew claws removed, along with shots.
Third, white is merely cosmetic. The std. states that a small amount (usually less than an inch or so) on the chest is fine, along with a few stray white hairs, typically on the chest or toes is also acceptable. AJ has a bit of white on his chest, and he is structurally superb, as are both his parents who are G.Ch. Again, good breeders look to avoid a lot of white, and if both parents have a lot of white, it would be a signal of poor breeding. The least of your worries would be the cosmetics, though, as this indicates laziness with the obvious, I'd be more concerned about the stuff you cannot see. Recall they are alive, and the result of their DNA and the early care they have received.
Recall that the quality of the breeding is what you live with, shop carefully. Yes, desire can be strong, but don't let it overwhelm common sense, the heart break that can result from poor breeding is incomprehensibly painful.