B. H. Mayer First Zeppelin Commerative Set

Hi, first please accept my appology if this is the wrong location for this post. I'm not a collector and know very little about coins.

I recently inherited a set of gold, silver and bronze First Commerative Zeppelin coins by B.H. Mayer.

These were purchased by my grandfather in the mid 70s and I've included a photo of the gold set below. They each have a corresponding certificate and the numbers do match across the 3 sets.



Curious if anyone knows anything about these and how I might assign a value. I've seen a couple listing for the bronze and silver sets but nothing for the gold.