Thus you would be wise to consult a table of Price Indices- such as the file "price10.TXT" released in 1993, before your evaluation of such figures is complete.
"United States Census Figures back to 1630"
U.S. Census of Population and Housing U.S. Dept. of Commerce, Economics and Statistics Administration, Bureau of the Census
Therefore, if the eBook is the 10001 plain text file created it will be named 10001. TXT.
"ERPANET Case Study: Project Gutenberg"
ERPANET