[5th_bike]

If it's just the crack and a ding (the ding is usually circular and caused by one of the signal lights being pressed into the tank): no big deal.
Mine had them too when I bought it, it still has the ding (and the scratches on the headlight, mirror, brake fluid reservoir and exhaust), and I replaced the front fender. I heard of a shop that can get the ding out but have not yet bothered.