In addition to everyone else's excellent suggestions: are your kids in preschool or elementary school yet? If so, ask the director or one of the other moms who she uses. When we first moved to this area and our kids were little, we were surprised to find that some of the elementary teachers did babysitting on the side. One in particular would do overnights for parents who were going away for the weekend.
Between the high school, a local house of worship, the elementary school, and neighborhood moms, you should be able to find someone without having to pay a service that you really know nothing about. Let that be your last resort.
If you lived in the Boston area, I'd send you my daughter, but your profile says you're in the southeast!
