Honestly, artists are way underpaid. You've mentioned before it takes about 20 hours for 20 seconds on average...And you work fairly fast... If you were getting paid in US minimum wage for the time you take on making these, you would be making 150 dollars a pop.
But people will be people, and they will be cheap. Thus forth, everyone who clicked that $20 mark, obviously doesn't respect the artist or the time it takes for something like this.
>:}D Anyone who pays $20 should get a blinkie. Only. Complete with color and background. Enjoy yourself.