Vanilla
In the 1930s, businesses made a group to choose prices.  The price of vanilla rose very high in the late 1970s after a big storm hurt important croplands. Prices remained high through the early 1980s, but then the group ended.  Prices dropped 70% in a few years, to nearly US$20 for one kilogram. In 2000, prices rose sharply again after another big storm struck Madagascar. The storm, political problems, and poor weather in the third year drove vanilla prices up to US$500 for one kilogram in 2004.  In 2005, the price went down to about $40 for one kilogram.  By 2010, prices were down to US$20 for one kilogram. It remains one of the most expensive spices.