Welcome to Automotive Forums. Most likely the brake light switch at the pedal needs to be replaced if the fuse is all right. Check the fuse marked "Stop". You can tell by looking at it if it is bad. It will have the little filament in the top that's melted. If not melted again I think it is the brake switch. As far as cost, you may be looking at a minimum of 1/2 hour of labor @ $60 to $70 an hour. You can easily replace it your self. Locate the switch near the top of the brake pedal and disconnect the electrical connection. Take the switch off and replace with new available at any parts house.