C.T.
This has been a sticky situation for me as well, but I believe I have figured it out. Even though I have cousins who get paid between $8-$10/hour (which even they say is rediculous), I pay my sitter, who is usually at home with me $4 when I am using her during the day and $5 when it is at night. You pay for what you get and if you don't pay your sitter's enough,then they won't take the job seriously because they won't care about coming back again. My sitter/mother's helper works Tues-Thurs from 10:30-around 4:00 and ends up making around $70/week. Not bad for a very mature 13-year-old who would otherwise be bored.
Also, food is always included in babysitting. Make sure they know that your kitchen is open to them! The more you make your house feel like their own and treat them like family, the more they will treat your children like family.