bi-polar is a serious mental condition that require a lot of special treatments and a total change of lifestyle, it's possible to overcome it and live a wonderful balanced life but that require constant work and dedication, almost everyone who has it would have relapses and though it can be controlled through medications and therapy, it's a chronic condition that would never really go away.
Saying that, would you trust a home test or cancer or HIV? would you really want to realize that you might be suffering from a serious chronic medical condition without a Dr. around to tell you what it's all about? I wouldn't.
This might be an OK tool to make a guess a little more substantial, however, this is not a serious indication tool and probably is at least partly a scam. Even doctors go to other doctors to have themselves diagnose, and so should you!
399$ can buy you about 4-8 session with a qualified psychologist. To me this seem like a better way to get diagnosed.