The first approach could be to build an app as inexpensively as possible - or for free. Although it's pretty incredible that you can do virtually anything these days for free, I think it's pretty safe to say that free doesn't always (usually never) mean well done. If you're on a tight budget, you might believe that something is better than nothing - but that is not necessarily the case. Your brand is closely associated with everything you put out there, so even the smallest of details should have a positive effect. With all of the technology at our fingertips these days, people don't just prefer quality, they expect it. If your app is designed poorly, has poor UX, or can't compete with other apps out there, there's a good chance it will get deleted - or forgotten.
On the other end of the spectrum, you could easily pay upwards of $100,000 for a quality custom mobile app. Sure, it's going to look fantastic, but there aren't many organizations out there that actually need an app at this level.