In an interesting post Mankiw has a bit on the ratio of text book prices to annual tuition. Now there is quite a bit of apples and oranges here. But it is worth the study.
1. Text books have expanded in complexity and useless fill in the last 150+ years. For example I gave my granddaughter an 1880 algebra book, she is going into 7th grade and completing that course. You see algebra has not changed a great deal. In fact current texts contain more confusing extraneous materials that a good old 1880 version is just fine. I used an 1895 Geometry one for grandsons and that was sufficient. And yes they all cost less than $5.00.
2. The production of text books, on the printer's side have dropped dramatically. The promotion costs have expanded. Getting someone to use the latest version of Calculus, and yes Macroeconomics, just pushes up the price, and the cost falls on sales not production. Nothing is new in Calculus, at least for the past 100 years. So get an old book for a couple of dollars and you are set.
3. Tuition reflects a lost more over head now than 150 years ago. Just think, there was no Title IX, and all the other mandated Government stuff. Text books did not do that.
4. Production efficiency in pedagogy seems to have been negative, less teaching student-hours and more other stuff.
It is a worthwhile observation but worthy of a great deal more insight.