I am in Plano (northern burb of Dallas). Most of our sitters were high school to early college aged.
When we used sitters, we guaranted $40 for the night even if we cancelled due to sickness or changing our mind because she saved the night for us. I feel that is only fair.
After that, we paid accordingly which was around $10/hour. Our date nights weekly ran anywhere from $60-$80 CASH. If you pay well, your sitter will tend to stick with you. I had girls calling me asking to come babysit our daughter because they knew we would never stiff them and we took care of them. In the end, our daughter has continued relationships with a couple of these sitters who are now in college and they are mentors to her.
Good luck