Caveat emptor. I'm sure there are folks out there that will pay those prices to have their firearms cleaned, and it doesn't hurt those of us that won't. Good for the business for providing a service that will benefit some of their customers, and hurt none of their customers.
It will probably take their employees much longer than quoted above to clean a firearm, since they are probably cleaning them in between customers and their other duties. Maybe they have an ultrasonic cleaning tank.
When I worked at Pannell's Firearms I would clean firearms for customers, but I don't remember how much I charged. I know it would sometimes take me all day. Also, you don't end up getting some guys Glock that he just put 100rds through. You end up getting a Remjngton 742 that belonged to the current owner's father, has been hunted with every season for the past 20 years, and never cleaned. Numerous rifles that I took in to clean I had to plug the muzzle, fill the bore with copper solvent, and let it sit overnight. Think green and fuzzy bore.