I suspect that many Mac users — as well as some aspiring developers — have only a half-conceived notion of the economics involved with becoming a successful indie Mac developer.
The basic idea is that a developer comes up with an idea for an app, implements it, ships it, and starts selling software licenses for, typically, around $20-40 a pop. If he can sell 1,000 licenses in a year, that’s a nice hobby. Sell 2,000, and he’s getting close; at around 3,000 licenses per year, revenue is probably in the ballpark range of a full-time salary. (Keep in mind, however, that, say, $80,000 in software license revenue results in much less personal income than a job with an $80,000 salary; salaried jobs tend to come with things like health insurance.)