Custom-your-page commissions?

After doing a big project for Cheferoni which involved coming up with some journal designs and page designs, I though of something: Maybe I could do this as a commission offer?
I just think this would be a decent idea. Since I'm a graphic designer and I'm used to the stuff that's involved with page decorating (coding, typography, etc), I could try to make money off of it.
What does everyone else think? What would be a reasonable price for everything? (like journal page designs and banners) I don't think I'd go through with this unless I get approval with a few people. I'm mostly terrified of this idea blowing up in my face.
(sidenote: I've done journal designs for people in the past, including my friend Mindsebbandflow, so I've had experience before, but for points rather than money)
BIG HONKIN' EDIT:
My friend Cheferoni asked me to make a poll with the possible prices, and since I don't have a PM, I decided to make up for it by making a journal of possible prices. I just need anyone's approval before going through with this.
Banners (examples: i1286.photobucket.com/albums/a… i1286.photobucket.com/albums/a… s1286.photobucket.com/user/Art…)- either: 
$5 a piece
$10 a piece
or 
$15 a piece
Journal pages (no examples for now, and I'm not sure why :C)- either:
$10 a piece
or
$15 a piece
Custom box backgrounds (examples: i1286.photobucket.com/albums/a…) either:
$3 a piece
$5 a piece
or 
$7 a piece
Let me know if this is reasonable or if you have suggestions of your own. Thank you!