Helmet price is based on vents, fit & styling. They all should have the certification sticker... after that, game's on! More vents usually = more $$, but will also cool your head in the hot months better. Adjustable inner stapping will allow you to fit the helmet to your head better. Style is style - you get what you pay for.

Best bet is to but past year's models new at a discount. After years of buying helmets for growing MTB racers, I generally found that the $30-$40 range provided them with a good fit & a look they were pleased with.

As lucille points out, you have to consider where & when you ride. Winter = fewer vents, darker color. Buggy? inner net lining. Very hot? more vents, light color.

The biggy is that when you dent or crack the outer shell, you need a new one. They are designed to break on impact, and that thin little shell evidently has something to do with the helmet's overall integrity and tensile strength.