Going by the book for college textbook savings no longer requires buying the book. Students facing a hefty annual bill for books can save an average 30% to 50% by renting that required reading.

This is the year of the textbook rental, says Charles Schmidt, a spokesman for the National Association of College Stores. About 1,500 of the trade group s more than 3,000 member stores will offer a rental program, up from 300 last year. That includes the 637 stores Barnes & Noble college division operates nationwide. Online rental companies are also reporting a spike. Comparison search site Cheap-Textbooks.com reports a 300% increase in book-rental orders compared with last year.

Separately, new federal regulations that took effect July 1 are also making it easier for students to cut their bill. The Higher Education Opportunity Act requires publishers to unbundle books packaged with extras, such as a CD or workbook, so students can buy only the components they need. Students often had difficulty buying just the book, says Nicole Allen, the textbooks program director at the Student Public Interest Research Groups, a consumer advocate. Regulations now require colleges to provide a list of assigned books at the time students register for courses. That should provide students more time to hunt down low-cost alternatives, such as buying used or renting, she says.

Renting is one savings strategy to consider, but it s not always the best deal. Before signing a rental agreement, consider these seven factors:

Rental availability

Renting may not be an option for all courses just yet. Rental companies and bookstores that are leasing books have to pay for them upfront. They recoup that investment over a number of semesters, Schmidt says. As a result, rentals are more widely available for core classes offered each semester, or where professors have agreed to use the same text for at least five semesters.

Edition updates

Renting is better than selling back in fields where there is rapid advancement, such as science or tax law, Allen says. If the professor orders an updated version of the textbook each year, bookstores or rental firms are unlikely to want to buy the old textbooks back at the end of the semester.

Competitive pricing

Just like purchase prices, textbook rental rates vary. Compare rates at the campus bookstore against those online, factoring in rental terms, as well as shipping charges and other fees. A student in New York could rent the text Money, Banking and Financial Markets for a semester for a total cost of $57.61 at BookRenter.com and $46.79 at Chegg.com, including tax and shipping. (Retail, the text costs $165.)

When price is the most important factor, check e-book options at sites such as CourseSmart.com, as well as used books through comparison sites including Cheap-Textbooks.com.

Coupon codes

Save extra with online coupon codes. Use the coupon code PIRATES at Chegg.com before Sept. 1, and get 5% off a rental. At BookRenter.com, code LOVE2RENT offers a $5 discount, and at CampusBookRentals.com, code RESOLVETOSAVE$ knocks $7 off the total.

Buy-back rates

Buying the textbook outright and selling it back at the end of the semester is not always the better option. The average rental costs 42.5% of the full retail price for a new book, while bookstore buyback usually maxes out at 50%, Allen says. However, there s more risk in the buy-back. If a professor opts for a different book or new edition, a seller could recoup just 10% of the original purchase price, if the bookstore wants the book at all.

Policy fine print

Check to see how much highlighting or margin note-taking is acceptable. Program policies also differ when it comes to extending or shortening rental terms.

Future need

Some textbooks may be valuable in future semesters, or even after graduation, Schmidt says. Although most rental programs offer the option to buy a rented text for the balance of its purchase price, students are likely to find better deals on the new or used textbook market. For example, eCampus.com rents American History: A Survey for $69.64 for a semester. Buying it new from the site costs $154.92 -- $42.15 more than its price at Barnes & Noble.