Around 5 cents. Even when the machines were first introduced in March 1960.
I remember 5 cents per copy in the 1970s during my first experience with copy machines. Some machines were 10 cents per copy. Coin operated at the WSU library where I grew up in Pullman, WA.
Meanwhile, house prices in Seattle, WA. have soared from around 20 thousand dollars in the 1970s to approaching one million dollars for the same house today.
Diverging rates of inflation.