Liability insurance

Can someone give me some advice on liability insurance? I know the hospital has it on me already, but in school they always told us to be sure and get our own coverage as well when we become a nurse. I asked my preceptor (I'm a new nurse, just passed boards) about it, and she said she doesn't have it. Her thought was, if you do what you're supposed to do, you don't need any extra. I understand her point, but my thought is, we're all human, and something is bound to happen at some point that was unintentional. If someone can tell me who they have theirs with, and approximately how much it costs per year, I would appreciate it.