My Fiance is coming back to South Africa from Bruxelles, Belgium. She has quite alot of luggage to bring home and the airline prices are just ridiculous. Is there a cheaper way to ship a bag from Belgium to South Africa?
In general, the larger/heaver the items, the more it costs no matter how you send it.
Some airlines waive the checked-bag fee for you (and sometimes your travel companions) if you have an affiliated credit card. They usually still charge overweight fees, but may allow two or even three items per passenger for free, so get an inexpensive bag scale and check the weight before you leave for the airport. Check the airline web site to see what perks they offer for holders of their affiliated credit card.
I often send stuff ahead using the postal service, which is usually the least expensive option. There are specific luggage services that pick up your bags at your house and deliver them to the hotel, but those usually cost more.