How to verify authenticity of toy story collectibles?

The only verified entity mentioned is Toy Story itself. None of the cited sources discuss collectibles, counterfeit issues, or authentication procedures. Therefore, based solely on the evidence given, it is not possible to describe any methods for verifying authenticity. Without additional reliable references, we cannot provide guidance on authentication techniques, provenance checks, or reputable sellers. Any answer beyond stating the lack of evidence would involve unverified claims.