Antimatter.

Cost: 62, 5 trillion dollars per gram. Antimatter is known as the most expensive substance on Earth, according to NASA's 2006 production of milligrams of positrons was worth approximately US $ 25 million. According to the 1999 one gram of antihydrogen would cost 62, 5 trillion. According to the CERN in 2001, the production of a billionth of a gram of antimatter (the amount used in the CERN collisions of particles and antiparticles in ten years) worth several hundred million Swiss francs. Antimatter in the future, it is theoretically possible to use as fuel for the spacecraft to other planets. The problem is that its production requires extremely expensive technology, and to create only 1 gram, the world would have to work for a year (global GDP is 65 trillion. Dollars).