Obviously, Disney Parks doesn’t want people who aren’t cast members to look like they are, and if people thought you worked there because you were wearing the same mask as everybody else, it would cause problems.
Nothing worn by Disney Parks cast members can be purchased as merchandise by guests.
Unfortunately, if you think this mask is so cool that you’d like to own one, you can pretty much forget it.
Even if you weren’t up to no good, you’d be annoyed by people coming up to ask you when the parade starts.