Where can I buy it? Can it be loaded into x8? It already has version 6.
Yes, it can be loaded into X8, but you will have to download a patch in order to increase compatibility.
Download patch: http://www.videostudiopro.com/en/support/updates/
Before installing, access the official website to download the latest version of installer: https://www.borisfx.com/products/graffiti/