User blog comment:NarriedAj/Founders Hats/@comment-34857455-20181127062156

I think it's mostly arbitrary. I use this guide mostly as just that. A guide. It's not even close to being a good approximation of value for me at least at most times, but usually, I just trade for what I like, and not what's rare.

Seeing as I think the game wasn't even designed with value systems in mind, I think it's all just player powered rarity/demand.