The best price found from United States to Cotonou is on March 1st, 2019, travelling with Ethiopian Airlines. See more options, compare prices and book: search flights.
The international airport is on the western fringe of town. A private taxi from the city centre to the airport costs around CFA3000, although drivers will demand double this amount from the airport. Zemi-johns will be happy to load you and your luggage for much less.