Personal situations such as this is most likely not appropriate on the forum not unless they are a listed seller, but even then, it should be kept out of here anyways...
Though I will offer my grain of sand.
3 years? I think it's pretty much a lost cause trying to get it back...They've been ignoring you, and they pretty much conned you good as I can see. Did you pay through Paypal? Did you have a contract? Paypal costumer service is horrible from what I heard, but this story seems pretty clean cut...but...you shouldn't have waited three years! They might ask you why and hold that against you.
That website over there doesn't really have good confirmation that it's reliable. Plus, that Kairi costume there looks really shotty anyway, and the Website doesn't really look updated.
Since it is most likely (and most unfortunately) that you will not get your money now, why not just post a formal review of this, with formatting and all (in front page) and warn other people.