You do not have to buy curriculum to homeschool. You do not have to have a "set" curriculum to homeschool. Your child will not be truant if withdraw her to homeschool without having purchased a curriculum.
According to the Commissioner's April 20, 2004 Home School Policy Letter,
"Students should be disenrolled by school officials when they receive written notice either by signing withdrawal forms or sending a letter of withdrawal. It is not necessary for the parents to make a personal appearance with school officials or present curriculum for review." (emphasis included in original document)
You are only required to provide a curriculum is designed to meet basic education goals including reading, spelling, grammar, mathematics, and a study of good citizenship. Furthermore, your curriculum may consist
"of books, workbooks, or written materials including that which appears on an electronic screen of either a computer or video tape monitor, or any combination of the preceding from (1) either one of a private or parochial school which exists apart from the child home or (2) which has been devloped or obtained from any source.." Final Judgement Leeper et al v. Arlington et al (Austin Area Homeschoolers)
The Texas Essential Knowledge and Skills (TEKS) is available on the TEA website and covers all grades. This is the state curriculum for Texas which "appears on an electronic screen." So don't panic and don't be bullied about your curriculum.