I think the problem isn't about skimping .. it may be more about (perceived) value for money.

$3K for the camera looked to be damned good value for money ..

But $500-600 for a $200-250 accessory is a murderous pricing policy!

it's obvious that a good many folks want such an accessory and I can't imagine how many more sales Nikon could achieve with 'respectable' pricing.