asset management site

Basically a simple site where there are different assets entered by admin. The assets change in value and so admin can update the asset value. Communication can be either for all users or specific user. A communication log saved. Users sign up and admin can add different assets to their list (each user has different assets) and upload document into user's 'document folder'. Total value of assets shown. (May be graphs to show growth/trend of assets - optional). We want very basic/simple pages and design (nothing complex). Users can have in house credits (updated by admin) to use to get more assets (optional). Any ideas or advice is welcome. This is phase 1.