Noncommercial tests (unpublished tests) are tests, scales, or instruments that have been developed by students and scholars. Unpublished tests can be found in selected books, and also in journal articles and dissertations. In general you will need to seek permission from the author to administer the test.
You can use APA's PsycTESTS to find non-commercialized full-text tests.
Commercial tests (published tests) are standardized instruments/tests that have been copyrighted as stand-alone tests or test kits. They are often purchased from a test publisher.
You can use Mental Measurement Yearbook and Tests in Print find information on commercial tests and instruments.