Why do you need a "killer app developer"? what it sounds like is that you do not have a technical side of the company sorted at all, and in essence you are betting that if you get a "killer app developer" they will do all of the technology for you. The reality is that augmented reality in retail is nothing new http://www.creativeguerrillamarketing.com/augmented-reality/10-examples-augmented-reality-retail/
and most of it has to do with the back end infrastructure and NOT the "mobile app". because the image analytics to build the recommendations on what is the best belt for an outfit is NOT part of the mobile app but rather the backend.
So I think you are buying yourself a bunch of trouble if you think your solution will be doable by a "killer mobile app"