I didn't see that guy on the website say his dogs were "Pit Bulls" he called them what they were.
I think if a breeder wants to sell their dogs for a penny to 100k, that's their business.
Most people have no idea what it takes, as in money-lots of it- time, timing, life balance, loss of work, to breed the right way. I am sure those dogs, like French Bulldogs, usually have to be done by AI then have a C-section done (not all). So, as a vet tech, I can add all those numbers in my head and tell you the approximate estimate to breed is around 7K to 15K, and I didn't add the stud fee. I want to meet the person who is handing out 20K for a puppy. I want to be their friend

lol. (kidding).
The owner of the link you posted has a 'bloodline' and his dogs look consistent. We may not like the look of his dogs (I don't like the look of many breeds) but a lot of other fanciers of that breed do. He took years breeding the right pairing together to get to where he is. He didn't take two dogs and just throw them together to try and sell them for over $10K.
I know a lady who sells her Chihuahuas for that much..$10k and up. The American Bully isn't the only breed.