Here’s one of the things I did last night instead of working on my thesis: I took the values in 1891 British Pounds assigned by James Gow (Companion to School Classics, 3rd ed.) to Athenian and Roman coinage and converted the value to 2005 U.S. dollars.
Rome, 49 BC (when Caesar introduced the Aureus):
Aureus (gold) (= 100 sesterces) = $127.53
Denarius (silver) (= 4 sesterces) = $5.10
Sestertius (brass) (= 2 dupondii)= $1.28
As (copper) (= ΒΌ sesterce) = $0.32
Attic money (age undefined):
1 talent = $30,067.15
1 mina = $500.63
1 drachma = $4.79
1 obol = $0.79
The copper chalchous, 1/8 an obol, would be worth about a dime.
I have no idea how accurate this is, but it does account for inflation from the 1891 values. Gow apparently based his calculations upon the quantity of silver used in certain coins and then the relative value of these coins to others.
If it’s accurate, it puts things into perspective, for example when Gow says that an artisan in the age of Pericles earned 1 drachma a day (= $4.79 US), and that a juryman made 2 obols (= $1.58).
Of course it’s impossible to say what the values were in different times and places, but a ballpark is better than a desert.