It is difficult to answer this question because every face is different.The number of Botox units injected depends on the strength of the "forehead muscles" you are trying to paralyze with the toxin to improve the wrinkles, both at rest and during "activation". Different people require different quantities of Botox in different areas to get similar results. A simple example is the following -- a man in his 30s will likely have a stronger set of facial muscles than a young woman in her 20s. He will thus need more Botox than the girl to obtain a similar result. Typically, I inject 15-20 units in the forehead and 20-25 units between the brows. So, if you are paying $10 per unit, this would range anywhere from $350 to $450. (**On a side note, $10 a unit is a very cheap price, and I would question the experience of the injector who quotes this price -- this is obviously exclusive of promotions, or a discount that may be provided for you...)One point I stress to all prospective Botox patients is to make sure they do their research when it pertains to their physician injector. The experience of the physician is more important than the price of the Botox. I think the key lies in truly understanding the anatomy of the injected area, and more importantly the variability in the anatomy between patients -- for brows, the forehead and anywhere else you plan on receiving a Botox injection. This includes having a firm understanding of the origin, insertion, and action of each muscle that will be injected, the thickness of each muscle targeted, and the patient variability therein. As a plastic surgeon, I am intrinsically biased since I operate in the area for browlifts and facelifts, and have a unique perspective to the muscle anatomy since I commonly dissect under the skin and see the actual muscles themselves. For me, this helps guide where to inject and where not to. However, with that said, I know many Dermatologists who know the anatomy well despite not operating in that area, and get great results. It should not be the price of the Botox, but the experience and education of the individual physician that should guide where you receive your Botox treatment.Always remember, you tend to get what you pay for.Good luck.