I can't really help with pricing but I would note that you need to consider how you will feed them. They will likely arrive hungry and they are capable of eating a lot. Either be ready to charge enough to cover your food costs or make it clear they have to send snacks for their kids.

Do you NEED this income? I feel like it could potentially be a draw on your limited time with your children after school and could also impact the alone time your children get after being at school all day. So I would seriously consider your children's thoughts on this.

I would also be aware that 2 days could become 3 days...could become... Are you prepared to either take one extra days of care or refuse their request?

While it is great to be able to help out families we know, it is important to make sure it is in YOUR best interests. The family sacrifices we make to provide childcare make sense when we need the income, but can be a bit burden on the family if we are merely doing it to help others out.