A 100 page comic book cost me $0.25 US in 1970 or so, it is a few US$ now.

A few dollars? 100 page comic books in the U.S. these days usually sell for upwards of $20. But comics are really another case where the product itself isn't directly comparable between time periods.The market has shrunk tremendously, so they try to make up the difference in volume by selling high quality "glossies" rather than the old low quality "pulps," for a larger profit margin per sale. In terms of physical quality of materials, it absolutely is better than what you'd buy in the 1970's, although arguably the quality of the materials doesn't have much to do with how entertaining the contents are. The writing is also completely different, since comics today target a very different age demographic than they did a few decades ago.