Well, to be fair, I'd be surprised if the number was any larger than that. Recording straight to CD in this day and age isn't what one usually calls a compelling proposition. Don't blame the store; don't generalize to others.
(NB, I'm sure the app is well-crafted and highly functional. But it seems fairly outdated, and the price point appears to be a little optimistic.)
That said, though, $35 a day after Apple's cut is $12775 a year for said app, assuming these scorching sales hold as average for the duration of the calendar year.
String enough of these apps together (or dust them off the archives), and you've got yourself a cottage industry. It's the iOS app store all over again!
(NB, I'm sure the app is well-crafted and highly functional. But it seems fairly outdated, and the price point appears to be a little optimistic.)