Generally, minimum household income must be equal to or greater than 125% of federal poverty guidelines for your household size (with exceptions, such as military background).
See this link and seek an immigration attorney for guidance, there are ways to establish the income requirement other than salary, particularly if other assets are owned (stock, prop., etc).
You have to read the instructions for the I-864. It is fully explained there. If you need more assistance, then consult an immigration lawyer.
Good luck to you.
Dean P. Murray
The Murray Law Firm
560 Sylvan Avenue
Englewood Cliffs, NJ 07632
Mr. Murray's response is NOT legal advice and does NOT create an attorney-client relationship. You should NOT rely on this response. Mr. Murray's response was generated without conducting a full inquiry as would occur during a face to face attorney-client consultation. It is likely that the response above may be made less accurate, or become entirely inaccurate, as you, i.e. the questioner, disclose additional facts that should only be discussed during a private consultation with an attorney. I strongly recommend that you consult an attorney who is licensed to practice law in your state (or, in the case of immigration law, and attorney in ANY state), whereupon all relevant facts will be discussed. All responses posted by Mr. Murray on Avvo.com are intended as general information for the education of the public, and not for any specific individual.
125% of the poverty line for a household your size plus the alien.
The above is intended only as general information, and does not constitute legal advice. You must speak with an attorney to discuss your individual case.