Some doctors charge per area treated with Botox and others charge per unit used. The face can involve many areas, such as the forehead horizontal lines, the glabella, between the eyebrows, the crows feet, the DAO muscle, the under jaw neck area. From person to person, the number of units vary per area. You need to have a consultation in person to evaluate your anatomy and determine how many units you would need. Sometimes the treatments are broken up into different days to minimize the number of units used at one time. Furthermore, different doctors may recommend different number of units for you. Different doctors also can charge differently per unit. Please remember that medicine, including cosmetic treatment, is both an art and science. Experience, skill, knowledge of anatomy and a gentle hand and artisitc eye are all important aspects of a provider's technique. Shopping only for price for Botox can lead you to a non-board certified physician or non physician provider. You would like to ensure your chances of getting a good result and being able to communicate your desires to your provider.