artists_beware | Game Character Designs

Hi, a friend recently introduced me to the group... my DA archive is http://ogawaburukku.deviantart.com

I live and work in Japan, and recently at a comic event some indies game makers came up to me, looked at my work, and asked if I'd be willing to do character designs for them. I was pretty happy to do them, since it would be an opportunity for me to do a medium I otherwise wouldn't normally get to do. Then they emailed me and asked me how much I usually charge for my services... sweet! I would have done it for free.

But, since I AM trying to go professional, I'd like to offer them reasonable pricing that doesn't sell myself short. In the past I've done designs for very cheap, because I have a habit of underselling myself...

When you all do character designs / commission designs, how much do you charge/buy them for? In the past I've done mascot designs for $50, which I know is cheap, but I feel like charging too much more than that per character would make these game makers run away to someone else. Since I am only just starting to do the event circuit here, this would be a big help to getting my name out there.

What's typical pricing for this sort of thing? I'm not a by-the-hour kind of artist, since I work at a different pace depending on my other workloads. When I've looked online, I mostly get either kids from DA and GaiaOnline selling their abilities for $10 or something cheap, or I see pros charging $300 for turnaround sheets and I'm probably not at that level yet.

For some idea of what sort of designs are required: http://fcmegabu.com/goods/maou/maou_spec/
I think the images are all still images.

Any suggestions or cautionary tales would be appreciated.