From the title, I really really thought this was going to be about paying for downloads to force your way in to the top charts. I'm very glad to see that this is actually a great success story instead.
Thanks! Have to say the idea of paid downloads has always been gross to us, definitely hurts the ecosystem and tips things over in favor to companies like EA who have cash to burn. We work pretty hard to pick up new fans, then produce apps that they'll actually find cool and pick up on their own :)
MacHeist, on which this is apparently based, sells a bundle of software for far less than their usual price. It's not the same as paying for downloads, but...