As others have said, I would really consider the IPIP options or the PID-5, both of which are completely free and have no strings attached. Just FYI, you can use the IPIP scales to basically create the NEO (a widely used personality measure, but one that costs money). That is, you can assess all five-factor model domains and facets with the IPIP scales.
Other free options include:
-The BFI-2 (which also is brief if that matters);
http://www.colby.edu/psych/wp-content/uploads/sites/50/2013/08/bfi2-form.pdf
-The HEXACO PI-R (60 or 120 item versions);
The HEXACO Personality Inventory - Revised
-The IPIP-120 (another big five measure that covers the same content as the NEO);
http://psycnet.apa.org/record/2014-24009-001
-The FI-FFM( another big five measure);
Development and Validation of the Faceted Inventory of the Five-Factor Model (FI-FFM). - PubMed - NCBI
As I hope that makes clear, there are many solid free options. I am biased here, but I think all of these measures also are stronger empirically than legacy measures such as the MMPI and MCMI, especially if you don't have some sort of specific clinical purpose in mind (e.g., validity testing in forensic settings). Good luck!