I'm with Gary on this one. I'm afraid I just don't see the appeal for a prospective buyer. I see on the comments that you don't see the distinction between the Android business card builder and a "Custom Android application builder". For me an application builder would do more than allow me to display some information about my company, it would let me build an application that does something useful. Of course writing a web app that allows anyone to do this without knowing how to program would be very difficult.
Saying that businesses will pay $199-$499 for this service strikes me as questionable, especially when you have no customers to show that. If there really are other services successfully doing this perhaps you should mention them by name so buyers can see there is a real revenue potential.
You say that to hiring a devoloper to produce a similar application would cost several thousand dollars, but I can't see ever charging that much to code what is essentially a business card. Similarly, if someone wanted to contract me to build this (Android Business Card Builder) app it would cost significantly less than $16,000. I wish you the best of luck, and I'll be keeping an eye on this. I think it would be nice to be able to build fun little web apps (and this one certainly looks like it was fun to code) and sell them without doing any of the marketing, but from what I've seen in the past people are more interested in sites that already have traffic/users.