Depends on your head. Go to a shop and try some on. Any of the helmets there will protect your head. As prices increase, you're paying for decreased weight, increased comfort, and a better looking product. A $100 helmet from Giro, Bell, Specialized, or any other company won't offer better protection than a $40 helmet from the same company, but you will almost certainly wear it more often.

If you like a sporty "cyclist" look, check out the above companies. If not, check out Bern.