You guys are not asking for much. Consider this. Rent in airports is high and beyond that most stores in airports think they can sqeeze that extra $, Rand or whatever. Usually its a case of I have to have it, therefore heres my wallet.
If you just plan ahead a bit you can avoid it.
As to the Credit Card etc, thats a different ballgame, here in the states its not the same problem. We dont pay for unauthorized use with reasonable behavior in purchasing products.
Lots of places to shop on line. I know everytime I come to SA I bring over new WAC charts as they about half the price.
I have been into those stores that Gulf mentions. They are very nice and have the appropriate things that I would look for in a "Pilot Shop" but the prices are out of touch with reality.
I do think a lot of that price has to do with "Sole Importers" for certain products. That is to say that if a store wants to purchase brand name things from the states they must go through "The" person who has the contract in SA. As an example, I can get Zippos here for the average of R70-100. Not going to happen in SA. Could be true for Pilot things as David Clark, Garmin etc.