[perpetualpatzer]

The discovery and cost structure problems are points a lot of people miss. Textbook publishers are selling professor time in the forms of content discovery, basic homework creation, and basic lesson planning.

One expansion on the principle agent problem: college bookstores handle. Many bookstores rent their land from the college with the agreed rent of $X +Y% of gross. This creates a disincentive for the institution to spend time negotiating with publishers (or ensuring faculty are getting enough use for the materials they assign).