Below are links to pages with current information on the things you must have before you apply for a Ghanaian visa. You have the option to apply directly to the nearest Ghanaian embassy or you could use one of the visa and passport acquisition agents listed for a fee.
GETTING YOUR VISA FOR GHANA
VISA HQ – They can get you a passport. And also a visa to practically any country. Caters to only US and Canada nationals
American Passport – Offering international visa acquisition services