California (Bay Area).
Hourly rate starts from $40 and goes up to $100 per hour. Average around my neck of wood charge $60-70 and hour. That's $600 to $700 a day if you're willing to work 10-11 hours. Yes many schools are experiencing shortage of instructors so you can have as many student and work as many hours as you want. Really a good time to be CFIing.
Of course cost of living is sky high here too... But if you are willing to live with the roommate and work like a dog, you can earn and save goo chunk of change.