Commission Pyrofrost

Commission for PyroFrost1
this is his second time commissioning me 
Thank you pyro.  

Anyone interested in commissions, these are my prices for the time being -->  Commission Prices (Opinions needed)I need your honest opinion on my prices for commissions.
I will be producing an actual price sheet with examples, but i need help with the prices.
Sketches
Headshot - $2
Waist up - $4
Full Body - $5
Extras: Background - +$2, Extra character - +$2
Lineart
Headshot - $4
Waist up - $7
Full Body - $10
Extras: Background - +$4, Extra character - +$4
Colour (Flat)
Headshot - $5
Waist up - $9
Full Body - $15
Extras: Background - +$8, Extra character - +$5
Colour (cell shading/soft shading)
Headshot - $7/9
Waist up - $10/12
Full Body - $18/20
Extras: Background - +$12/14, Extra character - +$7/9
Colour (Lineless, looks 3D or realistic)
Headshot - $10
Waist up - $15
Full Body - $25
Extras: Background - +$20, Extra character - +$15
I dunno, I somehow feel my prices are too low. Then again, I don't want them to be too high either.
PLZ HELP! 

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Art (c) zeaeevee 
Commissioned by PyroFrost1 
Time: about 2hrs, maybe less
Programs: Sai, PS CS6

Pokemon (c) Gamefreak