$300? holy crap! i knew it wasnt cheap, but thats about $250 past what i was expecting ! how much would it cost for JUST the fiberglass/bondo (no visor, leds, fans, etc), or was that what you were talking about?
$300 is a pretty conservative estimate. You have to consider that if you're looking to make it from scratch from fiberglass/bondo that you'll need to make a mold or make a pattern. You can't freeform fiberglass like clay or something.
So in terms of materials theres alot involved to make one for yourself from scratch.