I have a 2007 Versa and when I go to start it about 50% of the time a car symbol with a key displays on the dash. It only does this if the key doesn't sense the chip in the key I guess. When I put the key in the ignition switch and starts to turn the key I'll see this and I know the car isn't going to crank.

How do I know if I just need a new key ($120) with the chip in it which is expensive or a whole new ignition switch???????????