Are the requirements you refer to regarding exclusivity of certain fares to SA residents/citizens? I only ask because, as my family lives here, I do much traveling in the country with fares/deals "only for RSA residents" although I hold a US passport and only have a temporary residence permit. Not once, whether it be at the airport or a travel agent or a game lodge, have I been asked to prove my RSA residency status. Once I even mentioned I was not a resident, but because I was making the booking from within SA and with an SA agent, there would be no problem...

If you book the flights domestically and use an electronic ticket, or if you know someone who can do it for you, then you could take the option of the lower-priced fares.