Make a list of the book titles you are looking for. Write down the International Standard Book Number (ISBN) if you know it. This can significantly narrow down the search when you are unsure of the author's name, as book titles can sometimes be similar. It is a 10-digit number found on the back cover or spine of the book. You can also look it up online if you haven't seen the book in person.
Go to the search engine of your choice and type in the key words "buy cheap books online" and click on some of the websites that come up to compare prices. Popular sites are half.com, amazon.com, cheapbooks.com and bigwords.com.
Enter the title (and author if required) in the search box and click on the "submit" or "search" button.
Compare the prices from two or three websites in order to get the best deal. You may also read the condition of the book, as most websites require this information to be entered.
Add the book to your checkout cart and go to the payment page. Type in your credit card, debit card, PayPal or electronic check information. Double-check for accuracy. Add the shipping address, shipping preference and hit "confirm" or "submit."
Write down or print the confirmation number and wait for your book to arrive in the mail.