In a 2011 article, Martha Smith, a horticulture educator at the University of Illinois Urbana-Champaign, notes that in the 1620s, "Tulips were more valuable than gold. " Why were these plants so expensive?" Initially, the tulip was a luxury item only the wealthy could afford "She goes on to explain. Indeed, a single "Rembrandt-type bulb" cost the equivalent of $1,500 at the time, which was "ten times the annual income of a skilled craftsman or the price of a large house."