ReadWriteStart

Last month, Instapaper founder Marco Arment revealed that he'd pulled the free version of his popular "read later" app from the App Store. There were few complaints and sales of the paid version remained strong. Arment's action seemed to challenge the prevailing notion that a free app (typically an ad-supported app) is necessary or a good idea.

That may hold true for Instapaper, which has no doubt developed a strong lead in this space - a well-established and well-respected brand. Users have found value in the service, and so they pay.

But that $4.99 might be a harder sell for a new, relatively unknown startup.