Remember you get what you pay for. I've never experienced a damaging hydro surge living in the big city. If you are at risk at any time it's during a lightning storm for which there is no protection or when there's a blackout, big or small, and the power comes back on. Those happen. Also with the 'threat' of brown outs in the future, more exposure to damage will occur.
Most medium or high end stereo and tv stores will carry good quality serge protectors and can advise you. Depending on what you've got hooked up and the number of components in the system, expect to pay between $100- $300 for a unit.