Which mobile broadband has the cheapest topups

[skimread]

I am looking for the cheapest mobile broadband topups

With Afrihost I can upgrade my monthly package to R99 (2GB) however this only comes into effect from next month.
I can also sign up for a new package but then I have to wait for the SIM and the RICA process so it isn't instantaneous.
With Afrihost I can topup at 1GB but this costs R99 per 1GB instead of R50.

Which package (post or prepaid) will give me the cheapest same day 1GB when I need it only for that month

 

[sajunky]

Telkom PSB data promo (no roaming)
2+1GB R149 valid till the end of next month
60+60GB R1800 valid for one year

There are various one day or recharge bonus or other short term bundle from MTN and CellC, but I don't use it.

 

[NeonNinja]

MTN 1GB for R65 (week)
MTN 1GB for R85 (2 weeks).

 

[ginggs]

iBurst top up rates:
1GB R59
3GB R177
5GB R295
10GB R590

 

[skimread]

thanks guys