greatbasin

There's no evidence more expensive helmets provide more protection. I realize your dilemma allows for this with a cheap, heavy helmet that is protective. Besides lightweight, we could add aerodynamic, and effective ventilation. Some helmets can expensively achieve low coefficients of drag, with low weight, and good ventilation, all at great cost without providing good protection. Conversely, a helmet can provide good protection, but be heavy, hot, and not especially aero.

Specialized markets their S-Works Evade II helmet with this copy: "Helmets have long been plagued by an unspoken rule: Light weight, ventilation, aerodynamics—pick two, there's your helmet. As you can tell by now, though, we don't play by these rules—"

Notice they don't mention "protective." The Evade II flunked Virginia Tech's helmet testing. Despite its price in excess of $200, an $18 Schwinn helmet was rated substantially more protective.

I don't know how much credence to give VT's helmet testing. It's independent, it's objective, it's also unclear to what degree the results reflect protection from actual injuries. Nevertheless, it should be obvious that protection is not even the chief criterium for helmet design -- otherwise we'd wear full-face motorcycle helmets. Most people want something at least cooler and lighter weight, and cyclists that spend most of their time at 20mph or faster care about aerodynamics or they wouldn't wear those ridiculous lycra outfits.