rain offers a 4G data-only service priced at 5c per meg, R50 a gig. Only pay for what you use, at the end of the month.
You can add unlimited off-peak for R250 a month and get 19 hours of unlimited data between 11pm to 6pm the next day. Data used during 'peak hours' 6pm - 11pm will be charged at R50 a gig.
When you buy your SIM and/or device from rain you get 7 unlimited data days to use and enjoy. Once you've reached the end of your free unlimited data days you'll continue with pricing of 5c per meg, R50 a gig.