Most test publishers prefer to sell directly to a test administrator, not to libraries. Ordering information--publisher, address, price--can be found in EBSCOhost in Tests in Print.
There are a few collections of commercially-published tests on campus, for examinaton by qualified students and staff. Inquiry at these offices:
Tests in Microfiche. The University Library keeps this sampler collection of tests on microfiche from the Educational Testing Service on the second floor in the Periodicals section. TESTS IN MICROFICHE