What do you get, then, in a $200 helmet such as the Giro Lone Star Pneumo? In part, fashionthe Lone Star model of the Pneumo has trick red, white, and blue graphics that you won't find elsewhere. You also get more cooling; the Pneumo has more, bigger vents than most helmets. This means it weighs less, too. And, you're buying the newest thing, something you'll always pay a premium for.
What you AREN'T buying is more head protection. Helmets today all have to pass safety tests administered by the Consumer Products Safety Commission, tests that have largely supplanted the older ANSI and Snell standards. So you get the same safety level in the Bell Influx, which is only $79 and is a very snappy helmet (even has a visor, which I like in rain or sun).
Myself, I usually shop for helmets that were "last year's" model and find them on sale. Helmets benefit enormously from trickle-down technologythe features that are on the very best new helmets quickly get passed down to lower-priced models once newer stuff comes in. The 2002 Bell Ghisallo, for instance, cost $125 last year. Now you can find it for $80 at places such as Sierra Trading Post and Pricepoint.com. It's little changed for 2003different colors notwithstanding.
I think helmets should be replaced every three to five years, depending on how heavily you use them. Remember that, over time, sweat and sun will both degrade the materials used in a helmet. And, replace a helmet after any significant impact, even if it looks fine. I really don't understand people I see tooling around with an old Bell Biker helmet atop their heads, and I see it surprisingly often. I mean, today's helmets are lighter, safer, cooler, and can be had in many cases for under $50. Being cheap is one thing. Being stupid is another. Particularly when it's possible to be cheap AND smart.