I have a Huawei from FNB for R75 per month. Thought it would be great to move to a cheaper phone and get prepaid on one sim and a data bundle on the other. Dual sim works fine and all, but the screen feels so rough. Typing is a bit harder. The screen just doesn't feel as responsive as High Tier phones.
A lot of the the retailers like Jet, Game and CNA sell the Samsung Galaxy Duos phones of different models. On average usually about R300 more expensive than their single sim counterparts. But if you're not concerned about famous brands then the InnJoo Fire on Takealot is definetely worth looking at.