If you have a helmet that is over 3 years old, then replace it. The foam in the helmet breaks down over time, and even if it has not hit the ground in the life of the you owning it, it is best to replace it. All helmets come with a data of manufacture sticker inside the helmet.
What is the difference between a $35 helmet and a $200 helmet? In that they are all ANSI or SNELL compliant they all do the same thing. The cheaper helmets are heavier, and do not let as much air flow through them. As you pay more, you get more ventilation and they do get lighter. Some of the more expensive helmets come with Carbon Fiber in them. But all in all they all do the same thing, Protect your head during a crash or from hitting low level object.
