My point is that I'm not sure what this thread is about. The app being $1, I get. Doing custom portraits in return for buying the game, I slightly get. He's at a point where a few purchases matter, so he's paying for marketing basically. He IS charging a competitive rate for his work, it's just that we pay in advertising we're doing for him by buying the app. But when people flat-out start discussing that doing portraits for $1 is okay, that's just wrong. A custom 16x16 portrait as a one-off should be priced at at least an hour's work, AKA $20 or $30 minimum. Otherwise you're not only doing yourself a disfavor, you're also lowering the price for the rest of us.
The size can also be irrelevant, because I notice that I charge more for 16x16 stuff than for 32x32 stuff, as the 16x16 stuff tends to be clients that want me to squeeze an icon or similar into 16x16 space, while still being recognizable, which is an artform I overcharge for, as it's a specialization that only few people can do.
Here's an example of someone that wanted their logo done in 16x16 for some reason. Photoshop will fail to reduce this completely and even hand-cleaning did nothing to make the logo recognizable. I was approached by the client to tackle this problem and it turned out that changing even a few pixels around would drastically alter the branding.

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While I can instantly recognize the people in the original post for example, Joe's edit, while way more visually pleasing, is not instantly recognizable.