Dog breeding or more specifically American Bully and Pit Bull breeding can be a very rewarding experience and somewhat profitable in the long run if you do things the right way to start. No shortcuts, no good deals, just hard work.
"So where should I start?"
The most important thing I can tell you is, do your research. Look at other big time kennels like https://www.texassizebullies.com/ , http://www.muscletonebullys.com/ , or http://www.bossykennels.com/. Also, research some of the foundation kennels such as Daxline, Greyline, Razor Edge, Muscletone, Gottiline, Remyline, and many more.
Study them and see what they are offering. Try to understand what puts them are the top — color, structure, size, pedigree, awards... or all the above. Once you see what kind of dog you like then you can start looking for a dog to start you program. Break your list down into two sections, "what my dog has to have" — color, structure, size, pedigree, awards. "what my dog can't have" — medical conditions, structure, size, color, temperament.
Next, develop a plan. Factor in you living conditions, financial situation, and schedule. Is breeding really realistic for your life style. Once you have factored all of that in, start your search. Know what you want before you buy it. I would rather spend $3000 on exactly what i want and on a high quality puppy, then waste $500 here and $500 there and not see the growth you want.
After you have narrowed your focus. ask yourself, are you looking to be a "studder" first or a "puppy seller". "Studders" buy great males and advertise them to make money from stud fees. "Puppy sellers" start with a great female and pay a "studder" to use their stud.
This may not be what the "pros" tell you to do but this is what has worked best for me, if you're buying a puppy, and the parents look ok, if you cant google the great grand parents of that puppy then you have a $1500 or below dog.