Any inspector who is described in Section 20010 may accept voluntary contributions on behalf of the director. Such contributions may be supplementary to collections which are provided in Article 8 (commencing with Section 64691) of this chapter. Such contributions may be in lieu of the fees specified in Article 8 (commencing with Section 64691) if the promotion and research program is declared by the director to be voluntary pursuant to Article 7 (commencing with Section 64671).