By and large, many tests and measurements are available for purchase. There are not many options for free stuff (although there are some strategies for thoroughly searching for them in dissertations and as appendixes to joural articles and books.) Be prepared to spend some money to get a copy of that measurement. Also bear in mind that test publishers will in most cases send you tests via postal mail, which may take days or longer to arrive. Finally, remember that if you're looking for a test, you will also need a scoring key, or the mechanism by which to grade the test results. Finding a test for free means little if you have no idea how to score it. The following sources list tests which are commercially available:
Identifying tests and measures refers to sources that can help you identify suitable tests and measures by critera. For example, if you need a measure of anxiety in children, or a measure of self-efficacy in online learners.
If you're looking for actual tests and measures, please consult Finding Tests.