babysitting worth it?


so im a stay at home mom with my 8m old son and my husbands sister is out of school and her mom would pay me $100 every two weeks to watch her and her dad doesn't help with anything or doesn't pay child support and my mil works at McDonald's so she doesn't make much but still is it even worth it 100 bucks every TWO weeks ? id be watching her from 8am-2/3pm every day ... also dh pays all bills so its just extra money for me and the food isn't a problem. last time she paid me $150 so dunno why shes saying 100 this time and dh mom doesn't speak english so really no relationship with her at all.