S.
E.,
I am currently looking for a nanny myself and I came across a website called enannysource.com. I don't usually like web site services, but this one gives great information and it's a lot less expensive than some of the services out there. We paid $98 for a 1 month membership.
So far we've gotten some good responses. They have a free trial membership (you can't access the nanny's contact information) but you can see how many of them fit what your looking for before you sign up. Hope this helps. We also put an ad in our church bulletin and got a few responses from that.
S.