In 407 BCE, two sheets of paper to write an expense ledger cost 1⅓ drachmas, roughly six grams of silver. Using a rough estimate of 80g/m², two sheets of A3 paper are a quarter of a square meter, so weigh approximately 20g. Within a factor of ten, paper was worth its weight in precious metals in antiquity!

Related, in the land of Pechakucha