Recommendation? Hey guys, Gerber Miming knives?

[Minnesota Man]

Hey boys, I was kindly gifted this almost complete set for helping a friend's mother. I initially refused but she was persistent.
It's a vintage Gerber steak knife set. Yet I'm missing one any idea how to track one down? I don't plan on using it (yet) but would like a complete set.
Gerber Miming set https://imgur.com/gallery/GMnBf
Edit: some pen cartridge in the box? Any ideas what that's about?

 

[hughd]

That big auction site has singles.