Apply for financial aid. Depending on your family or individual income and need, you could qualify for grants (grants are given through government agencies without the need for repayment), government loans and scholarships. This could not only help with textbooks, but could cover some of your tuition, housing and transportation expenses as well.
Look for book grants through your college and/or through independent non-profit organizations. Again, these grants may depend on your family-based or individual need for funding, but no repayment is necessary. Organizations like Beans for Books allow students to apply online for grants ranging from $500 to $1,000.
Apply for book scholarships. These range from college, government and private providers and are typically based on either your high school GPA and/or achievements, or your current college GPA, if you've already established one. These scholarships are usually gift scholarships with no need for repayment and are also typically contingent upon maintaining an above-average GPA.
Apply for book loans. These could be available through your college, the government or individual organizations. Repayment will be necessary, but usually isn't expected until you've actually obtained a degree or drop below half-time enrollment.