Is there any type of database or reference that has been gathered to indicate relative production runs or rarity of specific models and colorways of yoyos?
You can always post in a thread relative to the specific yo-yo, and someone on the forum will probably know. But, unless the yo-yo was custom anodized/modified, I believe the best source is the yo-yo manufacturer. That is usually the most credible source of information. Most of them have a website, Facebook, or other means of email contact. You can Google to find them.
If you google the yoyos name and Colourway you can typically find the answers you’re looking for.
I’ve done it a few times and it usually pulls up an old YYE thread about it.
Works like a charm.