There are many airlines that are offering flights to South Africa arriving at any of the three international airports, which is Cape Town, Durban and OR Tambo International Airport which is in Johannesburg. You will find that most flights that are destined for either Durban or Cape Town will pass through Johannesburg anyway.
If you can schedule your trip to be between the months of June and December you might be able to get a discounted air fare. This because during the first part of the year; the place has a high number of visitors trying to avoid the rains during the winter season. Traveling mid week that is on any of the days between Monday and Thursday will also get you lower airfares at a discount.
There are a number of places on the internet where you can get information regarding flights to South Africa. There are travel tour companies that can arrange and book your flights for you and even take care of your accommodation requirements if you want. Booking your ticket online will get you a ticket at a lower price definitely and also bookings made in advance also qualify for a discount. Basically making a booking two weeks in advance of your departure date qualifies to be called an advance booking.
Considering the flights to South Africa you have direct flights and connect flights. If there is no real emergency then there is no need for you to fly direct because it costs more. If you compare the arrival times of the direct and connecting flights its normally less than three hours.
The prices also vary according to the time of the year. So it is not possible to get any fixed rates at any one time, estimates might be available at any one of the following: