Section 48. The principal at each school, subject to the direction of the superintendent, shall, at the expense of the school district, purchase textbooks and other school supplies, and consistent with the district policy, shall loan them to the pupils attending such school free of charge. If instruction is given in the manual and domestic arts, the principal may so purchase and loan the necessary tools, implements and materials. The principal shall also, at like expense, procure such apparatus, reference books and other means of illustration, as may be needed. Said purchases shall be made in accordance with chapter thirty B and within the purchasing guidelines adopted by the municipality where such purchases are made if such guidelines exist.