When it comes to fit, finish, and paying for brand name, I couldn't agree more with the saying, "you get what you pay for". When it comes to safety, well, I have yet to see any evidence than a more expensive, legal, helmet will protect your head any better than a less expensive legal helmet will. And it seems like if the more expensive helmets offered more protection rather than just more comfort or a better-known brand name, then they would probably be screaming that at the top of their lungs in their advertising.
When someone says to you, "if you have a $100 head then buy a $100 helmet", look to see what other protective equipment they're wearing (if any) and ask them what their other body parts are worth. If any of us based our riding gear purchases on what each respective body part was worth to us, none of us would be riding motorcycles because we couldn't afford it.