On day one, harvesters cut out these river reeds. And in 8 days, after drying, burning and filtering, the reeds will produce one of the most expensive salts in the world. Just one tablespoon of river reed salt costs about $1 in Kenya. Compare that to the 4 cents it costs locals for the same amount of sea salt. So how do producers make salt from river reeds? And why is it so expensive?