I don't think most vets overcharge. They are running a business, same as a doctor or anyone else with extensive medical training. They have rent or lease or mortgage to pay on their office, employees to pay, equipment to buy, supplies and meds to order. Include insurance on their business and health bennies, work comp, etc of the employees, taxes.
They would be foolish to work at a loss or near loss. They have to recover loss from non paying clients, the occasional "free" work they do for an emergency or tragic circumstance.
Think about it, if we didn't have health insurance or access to public health departments, how many of is would go to the doctor as often?
My avian vet charges $65 just to walk in. Then add whatever meds, tests and stuff. Even though I volunteer for a non profit, I pay all those costs out of my own pocket on any rescue I take in. It would be nice to get a break, but I never ask and I never expect it. If I am broke for whatever reason, I just do without something so I can pay the bill, whether it be cable or internet that month or whatever. On the other hand, I have called a vet and paid toward a bill brought on by someone in the duck rescue community who needed help. I figure one day it will be paid forward and maybe in the future I am the one needing help and I will feel I can accept it.
Life is a balance. In order to have what you want, you have to be able to balance your needs to get your wants.