Open textbooks are free, online resources that can replace traditional textbooks and save students money. The costs of traditional textbooks continue to increase, and this can particularly affect at-risk, low-income students. Few studies have analyzed student perceptions of open textbooks and how they influence academic achievement, but the emerging trend is positive. In the present study, I assessed student perceptions of an open textbook and calculated the subsequent cost savings. Although there were some limitations to my study, such as a low sample size, my results closely mirror previous studies in that most students had favorable opinions of the open textbook and would prefer to use them over traditional textbooks. The average cost savings per student was $81 for one course, determined using a novel method that does not assume all students buy new textbooks. These savings were likely important to the students, the majority of whom worked five hours or more and have received Pell Grants or other tuition waivers.