Subject to the initial approval of the Secretary or Chief Procurement Officer, the appropriate purchasing unit for the following entities may use the services of the Department to purchase services, materials, supplies, and equipment: a county; a municipality; a governmental unit in the State; a public or quasi–public agency that: receives State money; and is exempt from taxation under § 501(c)(3) of the Internal Revenue Code; a private elementary or secondary school that: either has been issued a certificate of approval from the State Board of Education or is accredited by the Association of Independent Schools; and is exempt from taxation under § 501(c)(3) of the Internal Revenue Code; or a nonpublic institution of higher education as provided under § 17–106 of the Education Article. Notwithstanding subsection (a)(5) and (6) of this section, the Department may not purchase religious materials on behalf of a private elementary or secondary school or a nonpublic institution of higher education. The purchasing authority under this section is in addition to, and not a substitution for, the purchasing power of an entity under another law.