They're not worth too much. My 2002 world banknote catalogue lists it at US$1.75 in Uncirculated (flat and flawless), and "face value" in anything less than that. The theoretical "face value" for 100 drachmai is currently 39 US cents; the drachma is now obsolete, having been replaced by the euro.
The notes were issued from 1978 up to the introduction of a circulating 100 drachmai coin in 1990.
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