The agency fee is like $7000 then you pay the aupair/nanny $215 a week for 45 hours worth of childcare, the aupair does all the cleaning for the children. So thats one less room you have to worry about. That is considerably less annually then the $2800 you are considering. The aupair just needs her own room and can share a bathroom. It is an ideal situation until the babies can walk and get around better.