Vodacom
(grabbed from another post I made)
I walked into the Vodacom shop in JNB airport and purchased a SIM card (ZAR 120), ZAR139 airtime (the local word), and 2GB prepaid data for about ZAR389, total of ZAR 648. They just needed my passport. With pretty heavy usage, the 2GB lasted the 12 days I was there.
MTN
(coming soon)
CellC
(coming soon)
Virgin Mobile
(coming soon)