Are you a US citizen? Has anyone ever filed a petition for him before, and when? Without knowing that information it is impossible to tell whether he qualifies to fix his status without having to leave the U.S. Thus, it is hard to tell exactly what legal services you need. You're probably looking at anywhere from $1500 to $5000 in attorney fees.
Different attorney have different fees.
J Charles Ferrari Eng & Nishimura 213.622.2255 The statement above is general in nature and does not constitute legal advice, as not all the facts are known. You should retain an attorney to review all the facts specific to your case in order to receive advise specific to your case. The statement above does not create an attorney/client relationship. Answers on Avvo can only be general ones, as specific answers would require knowledge of all the facts. As such, they may or may not apply to the question.