I work in the medical field and it is not illegal for him to write a proscar script.
He is a MD, he can write a script for any off-label usage he wishes. Sure, if he got careless and a patient had problems he could maybe be sued, but its not illegal. He is probably more concerned about the possibility of assisting the patient in committing insurance fraud, which would really fall on the patient, not the doctor.
If you want brand name proscar- go here
http://www.prescriptionskeywest.com
Proscar 5 mg - 30 tablets/bottle $95.00
its is very pricey, but you will still be saving money if you 5th it. And you know its coming from Merck, not some dung-infested Indian lab with elephant sh*t on the production line
screw that Indian garbage.