Plugins for Account/PDF Purchase

I’m looking for a plugin (or plugins) that enable this scenario:

1. I upload PDFs, set permissions so only users of a certain group/groups can download them.
2. User comes to the site, pays for the PDFs, is automatically granted membership in the appropriate group
3. User can now log in and download all PDFs that are available to their permissions.

Basically the idea is to sell PDFs via WordPress, but the PDF may be updated and new PDFs may be added to the bundle so it’s important that the user be granted permanent access to the downloads.

The method of payment isn’t particularly important. PayPal, Amazon Payments, whatever.

It’s important that I also be able to manually add users to the download permission groups at times.

Bonus points for:
-The ability to email all users of a group (to notify of new content)
-Free plugins (as opposed to paid)