I don't think a shock and a cup holder is worth the same. The problem is that shocks need to be replaced every now and then and cup-holders hopefully not that often. So economics take over - what does it cost to hold stock of cup holders in case one breaks - you can calculate the holding cost of shocks much easier!
That said at the price they charged you for a shock you can nearly buy Bilstein or Koni shocks which should theoretically outlast your car!
BTW, driving a car that only 40 odd were sold in the country makes the first point very applicable to me! It is cheaper for Audi to hold stock of A4 ash trays of which thousands were sold in the country than to hold stock of a S2 ash tray
