[tonyedgecombe]

Authors have the same problem as musicians.

And app developers.

[ZoomZoomZoom]

Sorry, but this applies only to non-fiction.

You can always make a usable app or non-fiction book, so you have one extra dimension of objectively measured value of your product. The first one, common to software and art, is the quality of the implementation.

[tonyedgecombe]

Applications just like music have a near zero marginal cost. This is why the app stores are littered with $1 apps.