[rguzman]

Since the work consists of adding to an existing application it is even harder to estimate than usual. In fact, so hard that it is not worth trying. A lot of the time could potentially be spent just figuring out how your application works and the good ways to implement the new feature.

That said...

As long as all the flows for the features are well-defined, I'd say it'd be doable to implement basic search, social networking, and some facility for static pages for $2k. It should be a few of days worth of work for a developer familiar with the framework/libraries your app uses.