It varies widely, depending on experience and type of practice. The APA (American Psychological Assoc.) does an annual survey, which is on their website. Just be aware that with managed care, earnings in this field are more likely to go down than up.
A starting child psychologist can make from $30,000 to $45,000. Between 5 & 10 years of experience they can make from $55,000 to $80,000. After 10 years of experience they can make from $80,000 to $100,000.