As a professional in the Travel Industry I do monitor flight rates the whole time… at the moment flying to South Africa has become much cheaper during the low season.
e.g. British Airways – Amsterdam via London to Jo’burg: 570 Euro inclusive taxes.
Flying from Frankfurt can also safe you a lot of cash, e.g. Emirates via Dubai to Jo’burg: 615 Euro inclusive taxes in September.
However the high season for European tourism, July and August seems to be much more expensive this year. I presume the airlines compensate their cheap tickets during those summer Months? Rates around the 900 to 1100 Euro for return trip to Jo’burg are common in August.
Some websites with cheap flights: