This is so that the hormones will not kill you or cause a stroke. Occasional the doctor may want to re-check you, at least until you get surgery. After surgery, you can go on a lower dose, and then you suffer the same risk as any person with normal hormones. You have to take hormones for life. The doctor visit can run a few hundred dollars, unless you have insurance to pay for it.
Some doctors charge more, some less.
I have insurance, so I pay only 8 dollars per prescription, myself. My prescriptions are for three months at a time, so I pay 8 dollars every three months. Twice a year or so, I get checked up on by my doctor, just to be safe. I like to be safe. That depends on your pocketbook, and personal tastes.