Sodium and sulphur are very cheap and easy to get, but not because of this. Sulphur is a byproduct of lots of different industrial processes, usually oil refin

Sodium and sulphur are very cheap and easy to get, but not because of this. Sulphur is a byproduct of lots of different industrial processes, usually oil refining. Sodium is most commonly extracted from seawater. Frequency of elements in Earth's crust is a pretty poor approximation for how easy they are to mine.