David Barnard, founder of App Cubby, made a few guesses at the financial incentives Sparrow may have had for selling themselves to Google:

In the 60 days between April 8th and June 7th, I’d estimate they made less than $30k, a run rate of just $180k a year. The release of 1.3 and subsequent price drop in mid June generated another surge in the charts, but look how quickly that trailed off.

The revenue spikes can help provide runway, but sustained revenue in the neighborhood of $30k a month doesn’t bode well for a funded company with a full-time team of 5.

While his overall analysis is interesting, and I’m sure incorrect, it’s his summary that caught me:

The age of selling software to users at a fixed, one-time price is coming to an end. It’s just not sustainable at the absurdly low prices users have come to expect.