How much does it cost to adopt a foster child age 16 in Arizona?

I have a friend who is in an abusive home, and is going to become a ward of the court (in foster care), soon. My friends family would like to adopt him, and we were wondering what the fee's are. I know it will take about 60-90 days for papers to go through, but i need to know the cost of the fee's quickly. He is sixteen years old, in Tucson, Arizona. Does anyone have any information? the family that wants him are a married couple with 2 kids (1 kid who is his friend), and they have been married for 16 years. Very good back round, and meet the income requirements. all we need is the fee information.