Babysitting fees

My DD will be 8 months when I go back to work. A relative that used to watch my now 7 year old as a baby (in her home about 25 minutes from my home) had has offered to come to my house to watch my baby, when I go back to work. We would need her to get the 7 year old on the bus (3 houses down -- less than half a block), then watch the baby for about 6.5 to 7 hours, and maybe twice put the tieouts on the dogs and let them outside. This would be Monday - Thursday only, all holidays off. Mileage for 4 days per week to my house and back home shouldn't even be a full tank of gas -- about 140 miles per week.

What is your thought on a pay rate? For comparison, the daycare we are on hold with will put my daughter on the bus and keep my baby all day for about $1180/month to start (rate decreases as baby gets older).