I'm with GLC1968 and IndySteel - in the US , all helmets have to pass CPSC (consumer products Saftey Commision) Standards. So, as far as Crash-worthy ness, they're all the same - the $10 one does as well or better the $200 one - take a look at www.helmets.org
My advice - try on some - see what you like - then buy a couple. That way you won't be tempted to wear one after you've been pavement surfing. I have two Giro Monzas myself.