IDIC pendants, all the scripts, even actual film footage from the set. Gene Roddenberry had collectors in mind even as the show was still in its first run.
Do you have a Gene Roddenberry autograph in your collection? If it’s on a Flight Deck Officer certificate then…probably no. But it’s a fun item anyway.
The Making of Star Trek is one of the most important books in TOS fandom, and Gene Roddenberry was an early advocate of the project.