Appointment went pretty well. Then 30 days later I...

Appointment went pretty well. Then 30 days later I received a bill for an additional $317.00 (total cost $416.00).
I was floored. How can a simple doctors appointment cost so much???
Being a self paying customer because the cost of insurance I had no idea that professionals were so content preying on heart attack victims.
I guess they're OK if you have the insurance or have a lot of money in the bank.