To be entirely honest, I probably wouldn't because if someone is asking me to pay them for advice on how to improve my business (a.k.a. consulting), I'd wonder why they're only charging me $100.

This seems like one of those areas where charging more would be a signal of value and competence.

My answer might be a bit North America-centric, though. I'm not sure how business advice of this type is viewed elsewhere in the world.

Overall, I think the idea is a useful one. But if you're giving good advice, $100 might be under-charging for it.

This interview comes to mind: https://www.kalzumeus.com/2012/09/21/ramit-sethi-and-patrick...

Only If this is from a well know entrepreneur, manager or dev working for a big name / successful startup, somebody I heard on some popular podcast.

The advice may be related to product, technology, sales, marketing, fund raising, hiring, operations, etc

Definitely. I think it will be important to clearly show the expert's identities.

If it would mean to sign up your first (or n') customer? Absolutely!!

Without hesitation, yes.