Allow access to use files in media library, but restrict access to uploading files

I have a multisite installation where individuals are only able to post articles and view entries from Gravity Forms. With use of the Members plugin by Justin Tadlock, I can simply customize roles. Now my problem is the capability upload_files is a light switch. If it’s on, users can access and upload to the media library. If it’s off, they have no access to the media library from within posts.

What I am looking for is the ability for the super admin to upload a number of images to the media library, and allow the users to access them for featured image purposes.

Does anyone have a slick way of doing this or a plugin that works?