Not sure about Texas, but the cheapest place to get them in N. California is A.I.M Tires located at Infineon Raceway. I've bought several sets through them over the years, and they are a quite professional, although small, outfit. They support all the local Toyo Spec class racers out here (Miata, 911, etc).
AIM Tire: American International Motorsports
No affiliation. Just a happy customer.
Q