Got an idea to make a lil extra cash at university.
There is a shop that sells reviews for classes which are good for tests. They charge a good amount of money and even are poor in quality (just lots of mistakes, the content is good, but it is not professional looking and lots of spelling errors to be corrected).
The idea is buy them and retype them up in better/shorter/more simplistic way and sell them for much, much cheaper.
Might try this tomorrow. Decrease price by 75%. Only need to sell a few to make money back, copies are free too at school. Small overhead.