Minimum rate here is $10-12 for one kid and for me we look at $15-17 for the boys and occasional hours for dd. We are considering a p/t nanny when the boys start kindy but at this point daycare is a more affordable option. I'm not sure where you are but you would never be able to get someone here (colorado) for what you are considering. I'd suggest looking up nanny rates in your area. I think sitter city gives that info even if you don't subscribe.
Marisa, mommy to 7 year old dd and 2 year old BBB triplets