I offered to fix an extension cord for a mate of mine. It was missing the socket.  I recall paying a really high price for cord socket from Redpaths electrical wholesalers some time ago. About $18 or so by memory. I thought I might check out the price that Bunnings Warehouse (a recently arrived Aussie hardware store) sell them for. Turned out it was only about six dollars for a socket!

Why such a huge difference?  Economies of scale?  Price gouging?

Unfortunately, the high price of spare parts such as connectors, lamps, elements, LCDs, motors, coils, armatures, mechanical assemblies, circuit boards, and all sorts of other stuff  is a real problem for the service industry.  It makes a lot of repairs uneconomic.