The once off cost is R50 per a sim. There is also a once-off delivery fee of R100. After that all you pay for is the data you use, at the end of the month charged at R50 a gig (5c a meg). If you choose to add unlimited off peak to your plan, you pay R250 a month for unlimited data between 11pm and 6pm. Data used during 'peak hours' 6pm - 11pm will be charged at R50 a gig. How much you spend is up to you this can be done by setting a spend limit on your dashboard.