I know I think its crazy too. I will never belive that there is $200+ worth of time and material in a helmet and I certainly am not that vain to do it for fashion.
But the most important part of riding is keeping it safe.
The best valued one that I've found and my daughters safety is in one. Troxel makes a dial helmet. They are lightweight and have a 1 hat size difference adjustment. The back inside of the helmet has an adjustment dial so it can be made to fit snuggly. If you can only afford one then fit it to you, but hopefully your,kids/relations/friends/strangers are all close enough to average size that no one has to ride unhelmeted. I purchased hers last year for $45. They are SEI approved.