6- Mercury
Price: $3,400 per gallon
You know what this is. A chemical element commonly known as quicksilver, mercury is a heavy silvery d-block element and the only metallic element that is liquid at standard conditions for temperature and pressure.
It is used in thermometers, barometers, manometers, spectrophotometer, float valves, mercury switches, mercury relays, fluorescent lamps and other devices.
For $3.400 you can buy yourself a gallon of mercury to use it on those stuffs.
Also the mercury it is used in lighting: electricity passed through mercury vapor in a fluorescent lamp produces short-wave ultraviolet light which then causes the phosphor in the tube to fluoresce, making visible light.
