How much for a person traveling from Ghana to US needs in to purchase tickets to US [closed]

This sounds very much like, I'm afraid, yet another variation on an unfortunately common scam. To answer your question: There is no definite amount; it depends on the duration of the person's visit and the specific activities anticipated during the visit.

Scammers commonly claim that they need a certain amount of money before they can get a visa, or to purchase a plane ticket, or some other prerequisite to their travel. They also frequently claim to be traveling from one of a small number of countries, prominently including Ghana and Russia.

Adding to phoog's answer about how much money: in addition to having funds to pay for the trip (and spending most or all of one's savings for a brief vacation will alone be disqualifying), the applicant (assuming that a diplomatic, dual-intent, or immigrant visa isn't sought) must rebut the US-legally-imposed presumption that visa seekers have immigrant intent. This requires showing reasons why the applicant would return home after the trip: spouse, children, other family, property, other savings or assets, job, etc.

Without proof to rebut the presumption, the visa application will be denied.