Take the 2-minute tour ×  I've just asked a question where Tyler
Durden wrote in his answer that paper was expensive at Euclids
time.  So I wanted to ask the question:  How did the price of
paper / papyrus develop over time?  But then I realized that it
might be impossible to answer it with a simple time-price chart,
even if one had all information.  So the question is: How do
historians evaluate if something is "expensive"? How are prices
of goods compared over the regions / times? Do already build
"comparison tables" exist?  What I thought of  First try:
Comparision with other goods  There are certainly goods that
still exist in comparable quality (I could think of gold, sheep,
cows, stone or ground), the ratio might be different. So simply
calculating    • n = number of grams of gold one had to pay for
100 papyrus scrolls   • w = price of gold in Euro / gram   •
price of papyrus in todays values = n*w  is too simple. But
eventually one could give multiple prices like that to give a
meaningful impressing?