Childcare Proposal

Hello Readers,
I live and work in NYC and I have two children who are 2 & 4. They both go to day programs during what is typically known as the school year. I have a friend from college with a daughter who will be starting college in TN in the Fall and she has over the years, repeatedly asked to come and visit, come and stay with us. Once we had the children, she offered babysitting. This isn't something I have sought out, however, if I were willing to allow her to come and stay with us for six weeks in the summer, what kind of salary/stipend do you think I should offer? I am thinking that I would put the girls in an afternoon program, so she would do mornings with them from the time I leave for work approx. 730- until 1:00 when the afternoon program started and then she would be free. She would of course be living with us and I would provide her room and board. Just for the sake of reference, the girls are part of a great day program and I don't need to do this, just thought I could give them a break from their routine and utilize a friend's daughter and help her earn a bit of money for college.
Thoughts?