There are shops in Luthuli that sell genuine/original electronics but most sell imitations. The hard part is identifying the ones with genuine products. When we were in Campus and early working years, we knew them by heart. That was after a lot of leg work and knowing the small things to look for, quality difference especially for music systems etc. But nowadays the volumes of fakes has gone through the roof and the imitators have also upped their game making telling the difference a ginormous task!
Why the differences in price. They don't pay taxes. Subtract 16% VAT, import duty etc. from the supermarket prices.
Unless you are in Campus and you have the time to do all the leg work and information on how to identify genuine products, which Luthuli shops you are likely to get them, stick to Mainstream supermarkets and appointed retailers.
Never count on making a good sale. Have the purchase price be so attractive that even a mediocre sale gives good returns.