your fear of this happening is almost totally unfounded. since a ball pythons bite is much more a warning than the fact, it wants to eat you.
If you get a bp you will get bitten, i'm about 100% sure of that, however it's not as if its gonna tear your arm off or anything.
I'm guessing your testing the waters about buying a snake.
Here is a great factor in buying a snake: they can live 20-30 years.