Belly/Baby shower! just got my first request!:)

A lady just emailed asking if I would do painting at a baby shower. She's hosting an overnight shower, (didn't know people did that) and there will be about 6 ladies there. She wants everyone to be able to get painted, AND do mom's belly!
I have NO CLUE what I will be charging for belly's, as I have never done one before. Based on my prices on my site, do you think I can charge a regular party price, but what should I add on for the belly?? My thoughts are $25. I am wanting to start small just to get the experience, then prices can go up. I know some of you think I'm probably working for pennies, and sometimes it feels like it. Especially when they give a $20 deposit first, then the day of the party you're only getting $30-$40 after the work. But I just don't feel I'm good enough and experienced enough yet to charge much more. Especially in my area.

Price your hourly rate and make enough time that you feel comfortable painting all the ladies and the belly.