Can Someone Tell Me How the Charges Are Made for Botox?

There are different techniques to injecting botox or dysport to get different results. Also the size of the area or how dynamic the muscles are helps determine the amount of botox to use. Men have larger foreheads and need a lot more botox than women as a rule. What is important is the results you get so don't go cheap or you are wasting your money and will pay more in the long run to get touch ups which are not free.
When your doc charges by the unit, you have no idea going into it how many units your doc feels you will need to accomplish the results you want. You yourself will under estimate the amount of units you need by such an amount that you will be shocked when you pay your bill, whereas if you know you want the crow's feet or frown lines or forehead creases done, then if your doc charges by the area then you know exactly what you are going to have to pay and you can plan accordingly with your money whether you can afford it or not right now.
It all boils down to your results and your doctor patient relationship. Even if he does a great job most of the time, there will be a 1 out of 10 times when the botox doesn't seem to work as well and a touch up is needed even in the best of your hands.

I agree that you should be charged by the UNITS, not the area. Some areas simply require more units, and that is directly proportional to our cost. On the other hand, there is usually remarkable consistency in the number of units needed--usually around 30 per area. We do quote by the area for that reason. It is very consistent for our staff and patients...no ambiguity. As a patient I would always wonder: did I "need" more units because I was dressed well and looked like I could afford it? Of course, if someone truly needed LESS units, I would adjust my fees lower. I NEVER adjust them higher!