Alternative Billing and Management System for Moderated Subscriptions?
 

I have a forum whereby I'd like to allow members to upgrade to a premium membership. The problem is that I need to be able to moderate the upgrades.

I searched around and on this board, and I've discovered that the vbulletin subscription feature doesn't support moderated subscriptions. I'm not particularly fond of using MODs because of my concern about having them work with upgrades.

That being said, does anyone have a system in place where they already do something like this?

I'd want to:
1) be able to process the payment via PayPal
2) be able to manage the recurring invoices
3) use the system also as a contact/client manager for these members. Recall that only these premium members on my site will need to give any of this information.

Here is the brainstorm of my potential workflow:

1. Member submits a request to be upgraded via vBulletin contact form, and includes the additional information needed for verification (e.g. last, first, website, for example). (There's a post on what to include in the email so they will know what information to send me).

2. Assume the membership is now manually approved after checking the information submitted by the member.

3. The payment then gets processed via PayPal. Once approved, I manually upgrade the user.

Here's where I see a few choices with step 3 of the workflow:
a. Generate an invoice using PayPal and email them the invoice, and then have them pay and enter the information (e.g. first, last, website) via custom fields in PayPal. I can then download the contact info as a .CSV or the like and integrate with something like QuickBooks.

b. Use an online "billing management system" such as WHMCS. Once I approve the membership, I can send them the link to my WHMCS site and they can then submit their payment and have everything processed with WHMCS, including invoice generation, etc. I like this idea because WHMCS can serve as a fully featured system. But it's overkill for what I need.

So that's the story...any suggestions and advice are appreciated!