"Artists Beware"

I have just received an email today from someone known as Thrifty Lizard about designing a lizard character for a video game blog. They want 4 - 8 different head shot sketches of character designs and then a final full color head shot of chosen character. Everything sounds legit to me, but I wanted a little advice before I go ahead and do this. First off:

Does anyone have any kind of history with this person? I haven't heard of them before and I'm just curious if anyone else had.

What would be fair pricing for this kind of commission? Normally I would go about with just the general head shot prices and then the full color head shot price. But being its a character design should I charge more? These are the general prices that I am charging right now: http://vanillin.weebly.com/commission-prices.html

Thanks so much!

~Vanillin