Angola is the most expensive city in the world for expatriate professional migrants mainly because almost all international standard goods and services have to be imported and due to the lack of infrastructure there are price premiums due to demand exceeding supply.
The top ten most expensive countries in the world comprise two from Africa (Angola) (1); Democratic Republic of the Congo (6)), two from Europe (Norway (2); Switzerland (3)), five from America (Bermuda (4); Cayman Islands (5); Barbados (7); Bahamas (8); Turks and Caicos Islands (9), and one from Asia Pacific (Japan) (10).
http://www.xpatulator.com/cost-of-living-article/The-Most-Expensive-Countries-in-the-World-for-Expatriate-Professional-Migrants_717.cfm