I am looking for an economics simulation game that was used in a HS
social studies class.  Each student received perhaps five or six
colored plastic chips.  Then there were certain rules for trading them
with other students.  Also, each color of chip had a value and there
were also combinations of chips that had additional values.  The goal
was to have the most valuable hand of chips at the end of the game. 
At certain points during the game the rules would change causing the
value of the chips to change.

A good answer would contain
1.  The name of the game.
2.  The rules of the game.
3.  Perhaps the source of the game or a place in which people could purchase it.