Helmets are a lot like boots though, gotta try them on beforehand because it might not fit right. I know the Giro helmets don't fit me right. I bought a Smith helmet for $40 on clearance (50% off) at a local shop and it fits me great.
My wife will kill me if I buy a snowboard tomorrow. Hopefully the boards aren't in my size or not priced right so I won't be tempted to buy.