Pepper has not been expensive since the 18th century. The Dutch, of course, know this (and wouldn't pay more than a fair price, either.)

However, the expression remains, and is common.

Pepper was indeed costly, for a few centuries; and its trade was profitable for the Dutch — critically so, during the rise of the great merchant power of modern Netherlands.

The word peperduur probably derives from the medieval French expression from which derives the modern "cher comme poivre.") French cuisine treated peppercorns as a superior ingredient, and promoted its use — although the commodity had been valuable since the time of the Roman Empire.

Native to a region of India (and even later cultivated only in areas nearby,) the pepper that Europe demanded, for cuisine and medicine, was available only in meager supply relative to demand — so it was costly.

The value of pepper in European markets attracted all the great shipping powers, from the Romans to the great Italian post-empire cities to the Portuguese (whose Vasco da Gama learned how to sail around Africa) to the English to the Dutch — who competed and battled with the Portuguese fleets for primacy in the market for this and other spices in the region of the Indian Ocean.

The story of the Netherlands' "Golden Age," in the 17th century, is a story that can only be told with reference to the spices of the "East Indies," and pepper was the main cargo. Pepper was at the center of the great merchant operations of the Dutch East-Indies Company (V.O.C.,) a military-commercial operation that made the tiny country the principal maritime power, and Amsterdam the richest city in Europe.