I don't mean to be disrespectful, but if the student can't afford the books/doesn't want to pay for them, how is he/she going to pay for (1) an IELTS tutor/course and (2) the test (a few thousand Baht)?
Unless the student in question has a very good grasp of the language, he/she should definitely enroll on an IELTS course or take a private IELTS tutor. Studying alone is not the best course of action for people who are weak in English. Time with a tutor, private or group, is the best way to learn the techniques and strategies to help candidates improve their band score. While our esteemed fellow ASEANNOW member Plern might disagree with the last suggestion, I assure you there are many good, experienced and passionate tutors out there helping thousands of students to improve their band scores. They must be doing something right! Just found out this evening that my private IELTS student achieved band 7.0 in both speaking and writing. Band 7.5 overall. Not bad for a "degrre-less, sketchy af farang" [sic]