This website will give you lots of choices in Texas by county:
http://www.findworms.com/directory/index.php?location_id=57

But as temps rise you may want to think more locally. Baked worms -- yuck.

You can also check the Austin Farmers Market where one of our members sometimes sets up a booth or your local garden center. (I bought a couple of pounds of worms from a local non-profit garden/community project. Travel time was under an hour and the worms were accustom to the climate.) And sometimes on vermicomposters.com/ or Craigs List you will find enthusiasts in your area who are willing to give you free worms to get started.

Good luck.