The key for a Tex-Mex place whose specialty is enchiladas, is the gravy. You can find dried chiles anywhere down here, even the lily-whitest grocery stores have tons of them, and the Mexican or Asian oriented grocery stores even more. Same goes for comino, Mexican oregano, smoked paprika, and the works.
The necessary cheeses are widely available as well, and of course tortillas. Really easy to source the materials, not so easy to make it taste as delicious as my favorite places do.