I always thought being a huge chain that builders warehouse was the cheapest around based purely on their size. But they are actually damn expensive on almost all of their stuff. Only since buying a new house have I had to visit them frequently, and I am sorry I didn't do my homework before and just assuming they would be the most reasonably priced.
I have picked up a number of items from them and after buying and then seen it elsewhere for cheaper. Example, bought some floculant for my pool, builders was R79 I think, walked into a spar of all places a few days later, R64.99 (not on special). I bought a impact drill a few weeks ago, it was on a huge launch special according to the sales dude, R1199. Check Makro today and its R999 (not on special).
So just a warning before shopping with them just check the prices elsewhere, you might be surprised.