youdao

Access to the Internet costs more, but compare these fees with just one paper programming manual, engineering reference guide, or college textbook; the cost is absorbed in fewer than four books.

连入互联网的费用会多一些，但是与纸质的程序设计手册、工程参考指南或者大学教科书相比，这些费用可被不到四本书抵消。

youdao

E-textbooks can cost half the price of a new print textbook.

VOA: special.2009.09.03

In a nutshell, renting a textbook will cost about half of what it would cost to buy a new book.

FORBES: The Future of the College Bookstore

We were looking for a new model to be able to reduce the cost of acquiring textbooks and, ultimately, it became a textbook rental model.

FORBES: An Interview with Dan Rosensweig of Chegg