This thing:

I think other goops are stat boosters iirc, but I couldn't find specific info about this one on subeta lodge. What does it do?

Nothing. It is a minion and it is food. There is no "use option" which is what is typically needed for a stat booster.

No idea why its so expensive, I have a dozen of them.

The goops being expensive is because of an issue with their drop/zap rates, I believe. It was brought up in this thread here: Check drop rate?

posted back in May that she would be looking into it, but I'm not sure if it's been adjusted yet.

Ah dang, I thought I had something really special. OTL Thank you for your help!