from experience, i can tell you high end support far exceeds $20/h (think 3rd level network and systems support).
$20/h is more in the 1st line territory.
In all fairness, support costs also include all of the techs' phones, computers, networking, software licenses for Teamviewer et al, and office overhead. So a $20/hr bill is pretty cheap for a minimum wage technician.
Hell, I am just a sysadmin/developer with minimum experience (2yrs) and make ~$32/hr.