Thanks for the responses.
The SNELL website has a list of all the manufacturers and models that recieved their rating. Based on this I picked up a HJC motorcycle helemet and the local cycle emporium. SNELL 2010 rated.
The most popular autocross helmet. You will see national champions with HJC open-face helmets. Mine would still be legal for SCCA Solo (M2000), but not for the more-stringent local council because we have to follow PCA and NCCC regs.
I went to buy a used Pyrotect SA2005. When I got there, the guy was wrong it was an M2005. I took it anyway for a $20 discount. It's essentially a copy of a Bell Magnum (Mag4).
I donated the HJC to the local Austin-Healey club as a loaner. Their insurance is from their national club, they are not a member of the local autocross council and M2000 is still cool with them.