What makes it so fascinating is the inclusion of actual numbers for both sales figures and (estimated) time spent on development. The results look rather depressing for any developer who likes the idea of providing a straightforward product and charging a reasonable price, rather than using backhanded mechanisms such as in-app sales or advertising.
One subjective point, though: I had never heard of this application, and at $4 it’s the sort of thing I might well pay for myself (as someone who does pay for Android apps).
To get started all you need is an Android 2.2+ device and an Instapaper subscription account. A subscription account costs $1 a month and allows you to use third-party applications (such as Papermill) with your Instapaper account.
So to evaluate Papermill, you not only have to pay for the app, but also go and set up a subscription payment for Instapaper, which is a separate service from a different provider. And Google give you 15 minutes to get a refund if this combination doesn’t work out. (I suppose at least you can get a refund.)
I’m not really surprised that few people actually get around to doing this, no matter how little the sums involved. I think perhaps commentators are making the mistake of assuming most people have already used Instapaper.
Meanwhile in his linking article, John Gruber writes
Apple may never release a new non-high-end phone, but they do have mid-range and low-end smartphone models: the iPhone 4 and 3GS.
The 3GS costs £319 off-contract: that’s about three times what I would think of as a low-end smartphone.