I use online shopping when I can with normal household things, find prices are usually competitive, but the delivery can be excessive. I don't mind paying R55 (or whatever) if I can have everything delivered once a month, but R55 for one small item would put me off.
I don't think your shop even needs to stock a range of things like BabyCity. Just all the different nappies, wipes, formulas, and a few types of bum cream, Purity, stuff like that. One can always go and buy speciality items like bottles at an actual store (because you don't have to do it on a regular basis).