Thank you. This seems like a great idea. I would be more open about it. Rather than fees and membership, I would have a list of contributors and cross-checked publications. Basically like a resume. I.e. if you want to announce a vuln we would help you timestamp it, and optionally have a person you trust vouch for its authenticity. And if having that timestamp and cross check is valuable to you then you can brag about it when you contact the vendor.

I'd like to work in an organization like this. I'm not sure if anyone would want to join. It seems like everyone else is either completely independent like my own IDJGAF strategy or they are full corporate like HackerOne and other brokers.