Keith,
Just buy one that has the Snell SA2000 designation and you'll be fine for SCCA, NASA, and almost any other racing organization. The extra cost in a lot of helmets pertains to options dealing with fireproofing, style, and mostly ventilation (cool pack hookups, etc.). I bought an RCI helmet from Summit for $250, but I didn't realize it was made in China. I suspect the Simpsons, Bells, etc. are American made. I hope I kept you entertained down at 14 this past weekend. Nice to have met you and thanks for all your help. Damn nice Unique too!
h dog