You can try DHL or Skynet in Luanda.
DHL Express Head Office: Angola
DHL Express conducts business for Angola in the following location.
DHL International Ltd.
Avendida Khane Nkrummah 274/276
G/F
PO Box 1545
Luanda
Opening Hours
Mon-Fri 08:00-18:00
Sat 08:30-12:00
Sun Closed
Holidays Closed
I am not sure what you will pay, but you can always phone and ask, it depends on the weigh off course, I paid in Dec 2011 for exam papers back to the UK about $90 and the weigh was around half a kg or 0.5kg
Unfortunately I cant find any office locations for Skynet in Luanda.