I got paid $15 per hour as a CFI when I started out at a busy flight school, however they were charging $35 per hour to their customer.
I then got a raise to $20 per hour as an Instrument Instructor.
After 1600 hours of instruction, I got sick of paying $15 per hour to the management for 'facility use', then left the school, as relations were going down the tubes between staff and management, and management and customers, and airplane and maintenance!
I now am freelancing, and charging $45 per hour, and remaining busy enough to pay bills, rent etc.