Inside The Most Expensive Science Experiment  Ever Many machines over the past 60 years have been billed as the one that will make the big breakthrough in fusion science, only to stumble. This one could be different.By Daniel Clery 06.27.2013 Inside ITER Graham Murdoch cost: somewhere between €13 billion and €16 billion. That makes it the most expensive science experiment ever built--twice as expensive as the Large Hadron Collider at CERN.