Typically at a good piercer, it will cost you between $40-$60. You never want to go to a low rate piercer. The appliances must be sterilized properly or you could get an infection. You will have to spend additional money to purchase the jewelry itself. They will always recommend a gauge and simple silver barbell for your first piercing.
I would say between 40 and 60 dollars maybe more, it would depend on where you went. Make sure to go to a reputable body piercing place to get the best. Also make sure you keep it clean and dry to avoid any infection that may occur even after it heals.