Two cents per inch is the going price at the LQS in my city. You provide the batting. Some also charge for thread, some don't. This is for computerized quilting, not custom.
Sometimes when you get out of the city, you can get some deals on quilting. My cousin sent the name of someone who quilts for someone in her church. She charged significantly less. However, when I called, she said she was full right now. I decided to wait until after the first of the year to call again. She's about 65 miles north of the city.
bkay