As far as the face value equivalent in US dollars is concerned, the question is hard to answer. At the time this coin was issued, the Greek drachma was pegged to the US dollar at 30:1, so this coin was intended to be identical to a silver dollar. The Greek drachma is now obsolete, having been replaced with the euro in 2002, but between 1973 and 2000 Greece suffered from worse inflation than the US did, and the drachma was eventually pegged to the euro at 340.75:1 in 2000.
Currently, if you convert US dollars to euros and then use that original conversion ratio of euros to drachmas, you get 30 drachmas equal to about 13 US cents.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis