Depending on the amount of Botox used the price will vary. Typically Botox varies between $10-$15 dollars per unit. Please see a board certified plastic surgeon for best results.
I highly suggest you get a consultation with an experienced injection specialist. This will help determine how many units and the best course of treatment for you. Typically, a unit of Botox can range between 10-15 dollars, but for your safety it is best to go to someone experienced and not just based on price.