HOWEVER: everybody has a different opinion of what is meant by "Minimum", "Viable", and "Product". $5k gets you only bog-standard UI components and a simple data model. Animations? Fancy graphics? Optimized performance? Search? Custom UI? Graceful error handling? Localization/Internationalization/Translation? Integrating with Facebook and dealing with their constant poorly-documented changes to their API? These tend to be little bullet points in the spec, but each on their own can take as much work as the MVP does.
With modern tools it's pretty easy to build a basic version of an app quite quickly. But it turns out that most people don't actually want a basic version. Often they have to see the basic version first to realize that, though.
So the question ends up being: how important is schedule/cost to you compared with details/performance?
To be honest, though, most people who come to me wanting a simple iOS app are better off with a mobile-optimized webapp instead. Much quicker to build, already cross-platform, and no deployment delays while waiting for App Store approval. Mobile apps might not be as sexy as a native app, but saving lots of money is also pretty sexy.
That's because your experience is limited to development only. There's a lot more steps involved in making a successful app or a site. Brand identity, architecture, UX design (mockups/wireframes), and UI design are all steps that have to be done BEFORE development even starts. The cost of that can be 20-30K by itself.
There's also the cost of QA on different platforms, system analysis, professional copy, etc. So yeah, his quote is actually on a low end.
Too many people seem to think that they can get away with hiring a developer only.. then they wonder why their app/site doesn't do as well as they wanted it to.
Source: I run a web/mobile development agency.
I've done full-cycle apps with branding, architecture, UX, QA, promotion, etc. and yes they start at $30k - but they're finished polished products, while the discussion here seems to be about MVPs.
As I said above, the biggest conflicts I see between developers and clients are over the meanings of "Minimum" "Viable" and "Product".