Here's a so called Tetradrachm (thus the equivalent of four drachmae), an Athenian coin from the classical period. I reckon that one Drachma was the normal pay for a worker (depending on what he did and how skilled he was) and it might be of interest to compare it to the passage below.
"Do you think you are accusing Anaxagoras, my dear Meletus, and do you so despise these gentlemen and think they are so unversed in letters as not to know, that the books of Anaxagoras the Clazomenian are full of such utterances? And forsooth the youth learn these doctrines from me, which they can buy sometimes for a drachma in the orchestra and laugh at Socrates, if he pretends they are his own, especially when they are so absurd!"
Plato - The Apology 26d-26e
Translated by H.N. Fowler 1966