Easiest/Cheapest way to get from Madrid to Ghana and back?

I am studying in Madrid, and a friend is studying in Accra, Ghana. I am wondering the easiest/cheapest way to get there. As an American I have found that expedia and other travel sites are either overpriced or take like 3 days travel time just to get there. I was wondering if there are any other routes (boats, trains and other things) I may not have found out about yet? I am trying to keep travel prices under 850 or so.