A white & black American Bulldog is actually a white dog with black markings all over its body. The black color of the coat comes in patches over a white base color, with each individual dog having its own unique pattern.
Since white is the base color, this combination is registered by the AKC as white and black. Though registered, it is not counted as a standard color for this breed.
A black & white American Bulldog puppy is likely to cost between $1,500-$3,500.