My mom has had three doctors since about '07 and they have all been mainstream doctors and they have all had her on Armour. I know she is just generally low, as she is now 88 but not one has had her on synthetics. It started as a first step in addressing her Alzheimer's because that was the reason we took her, to start with.
The point is, it shouldn't be that hard to find a gp or internist who will have you on Armour. Have you shopped around for another doctor? You said your first doc was pricey, and mojolissa commented that the Armour costs more, too, but at Walmart, it's 30.00/month for her. I know she has medicare part D and her supplemental insurance might make some difference as well. I know her Namenda would be over 350.00/month without the supplemental policy and it is 6.00, as it is. So, point being, I don't know how much the Armour is, but if you have any prescription coverage at all, it shouldn't be too bad.