It’s back to school time and on top of a crippling $30,000-a-year tuition, students are required to pay a pretty penny for text books. A recent study by the consumer group, I-Team, reported that textbook prices have nearly tripled in the last 20 years. In fact, an average college student spends a mean of $667 on required course materials per year, reports the National Association of College Stores.

How can students buck this rising trend of textbook costs? You may be able to cash in on federal credits and find inexpensive textbooks or alternatives online. Under President Obama's American Recovery and Investment Act, you may qualify for a tax credit on this year's textbook costs. And another answer to the skyrocketing textbook costs has been an influx of websites offering cheap textbooks.

Here is a list of the top money-saving textbook resources:

Flatworld Knowledge — Flatworld Knowledge pioneered the concept of open textbook publishing — enabling content to be customized by professors. Students can browse chapters online using their computer or smartphone device or buy a bound copy. Although the site provides rich learning materials, students might have difficulty finding comparable content to their $250 textbook.

Chegg – As of this writing, Chegg has saved students $255 million, according to its website. How? It serves as a marketplace for renting and selling textbooks and even has a social mission, whereby Chegg plants a tree for every book rented. The online textbook site has planted over 3 million trees, so you can save money and help save the environment while you’re at it.

Campus Book Rentals – As indicated in its company name, CBR’s focus is on rentals. The textbook site has saved over 5,250 students money through rentals. Benefits of CBR include: free shipping both ways, 30-day risk free returns, adjustable rental periods and live customer support.

Affordabook – Affordabook searches eBay, Amazon, Half.com among other e-commerce sites to find the most affordable book option. For instance, a quick search for William Faulkner’s As I Lay Dying, will yield $10.25 from eBay, $10.77 from Amazon, $13. 69 from AbeBooks.com among many others. Affordabook does the searching for you so you can save time and money.

Google Books – If you’re required to read a classical work, such as Dostoevsky's Crime and Punishment, don’t buy the hard copy for $30 at your college bookstore. Google Books has the rights of thousands of books available for free, including Crime and Punishment. The book tool even enables you to add bookmarks to your library, organize your collection and share your books with friends.