Go to Pro Am Auto in Houston:
www.proamauto.com
They sell to SCCA and NASA racers, plenty of SA helmets to select from.
Telephone 713-781-7755 / 1.800.847.5712
Fax 1.713.781.8207
Address 6125 Richmond, Houston, TX 77057
Hours: 9:30am to 6:00 pm CST Monday thru Friday
9:30am to 4:00 pm CST Saturdays