Well the little yellowish one is quickly turning red under his beek. I see wattles! WAHHHH. He's soooo cute and lovable. Spoke to the boy, he will replace them. What a nice kid. Still not sure about the black speckled one. The comb is larger than the white one, but it's not red really. The white ones comb is very small, and pale.
If I were you, I'd ask the age in weeks. If they don't know, move on to another breeder. I think when they are this young, the breeder should know. If they are a week or two off that is not a huge deal, but these birds are months younger then he said. Don't get a bird that is not fully feathered unless you are prepared to raise chicks. I have never had an 8 week old chick that is not fully feathered, but there are breeds that take longer than others. Don't pick out anything with any amount of wattles or a comb that is noticeable. Hope you don't think I'm being negative! I always know the exact age of all my chicks born here. I have a lot of groups too :S Here is an example:
These chicks are 8 weeks old. Seeing the red in their combs, in combination with their wattles, they are both boys.
This is a female. She is 15 weeks old. Look how small her comb is? She only has 5 weeks or so before her first egg.
These chicks here are 4 weeks old. All girls. Barred rocks are sexable once feathered out a bit by colour. Boys will have more white then the girls.
Here is a barred rock pullet @ 7 weeks. Just thought I'd point those tips out when you go to replace them

Since the nice boy doesn't know what to look for. Not saying he is not nice because of it at all! Just so you know. One more:
Colour difference between the barred rock genders. Darker is female, lighter male.