Hello,
I cannot speak for the Dallas Fort Worth vicinity but I have been to G&G Model Shop in Houston right off Kirby just a few blocks south of Freeway 59.
When driving down Kirby after you get off the freeway, if you pass a big horned armadillo, you are headed in the right direction!
http://www.gandgmodelshop.com/
I think there are other hobby stores in the area but as I was on a tight schedule and only visited this one.
Cheers!
+Y.C.