I want to practice drawing some more, but I'm having trouble coming up with ideas, so I was thinking of opening up for commissions and like... whoever's interested can throw balloons at me to blow up or something. Only thing I'm stuck on is pricing, about which I'm kinda clueless.

So I ask you, friends and watchers: If you would be interested in commissioning a picture from me, how much would you be willing to pay for, say, a flat color or shaded picture?

Examples:
Lineart/Sketch, maybe $10-15
http://i.imgur.com/MENFf8i.png

Flat Color, $15-20?
http://i.imgur.com/tq0kWBR.jpg

Flat-shaded, maybe $25?
http://www.furaffinity.net/view/19357900/
http://www.furaffinity.net/view/19030867/

More complex shading/lighting, maybe $35??
http://www.furaffinity.net/view/19159035/