700/14 gives a price of $50/m^3^ or so, and 14 m^3^ makes sense because air weighs around 1kg/m^3^ at sea level (where the helium is measured for trade). Unfortunately, some fucker named a cryptocurrency "Helium" so it's hard to find, but I did turn up this. Due to the situation in the Middle East it could even be multiple times that right now.