How much to ask for in babysitting?

I know this all depends on circumstances, but in my case what if someone was bringing their 2 month old to my house for 10 hours a day 2-3 times a week, how much should I charge? I do not know this person either. I hear some say I should charge $10 an hour and others say $30 a day.. I feel as though $30 a day is not worth it to me but $10 an hour might be too much to ask for? Opinions?