How to Require Approval for Paid Subscriptions?

[Taipa]

I run a business forum for a small collective. Buying a paid subscription to the forum allows users to pay for their membership dues.

I need to be able to "screen" new paid members, to ensure that everyone trying to buy a paid subscription meets the requirements for joining our collective.

On top of that, I need to keep the ability for anyone to register to the forum itself, so potential members can create an account and post Pre-Sales questions, so I can't just moderate all new forum members.

Since these requirements are external to vBulletin (ie are completely unrelated to post count, or forum membership length, etc) I'm not sure what is the best way to set this up. I found ways to automate it based on forum-related qualifications, but we're checking external things like "does your website display a privacy policy".

I essentially want anyone to be able to register to the forum, but then members must apply to join the actual collective (two separate moderators will check each applicant, so they can't just apply by PMing me), and once they are approved, then they will be able to see the Paid Subscription option, and be able to buy their subscription.

Any hints on the best way to set this up?