This information is not a secret, there are just too many variables to give an answer. Are you part time or full time? Are you sole proprietor or do you have partners? Can you handle the stress? How devoted to the business are you? The answer to how much do you bring in? - is anywhere from millions to bankruptcy. Just some advice - Do not start you own business for the money. Do it because you want to be independent. Do it because you want the challenge. Do it because you want to make the decisions. The money is sometimes slow in coming - sometimes never comes.