Well, you know, things like chemistry and math don’t change that much. Calculus was invented in the 18th century.
It seems that an honest professor would buy a ‘wal-mart’ priced book and just fill in the additional information.
For math, physics, chemistry, statistics…there’s Schaum’s outline series which itself is updated periodically – all the basic information, example problems (solved) and test problems. These volumes used to run about $12 a couple years ago, and are probably still cheap versions.
Keep iin mind, last week Allan Greenspan said that there was virtually no inflation in this country. To natural gas, gasoline, health care, food, milk, autos, prescription and OTC meds, add textbooks which are spiraling out of reach.