Rochas Bakery in Mission, Texas. As recently as a few months ago the price for a breakfast taco, one filling, was $0.59 each. Flour (made there) or corn tortillas. By one filling I refer to the usual things mixed with eggs, beans, etc. I think Barbacoa is $0.89 a taco. They usually have about 12 choices, i.e. potato and egg, bacon and egg, bean and chorizo, nopales and egg, etc. When winter Texans are around the wait can be as long as 20-30 mintues to get up to the counter to order. Mrs. Rocha told me that on a busy Sunday they will sell over 200 dozen breakfast tacos.
These folks started with a section of a closed gas station and now have free standing 3 stores, all in the Mission area, and their daughter is an Aggie.
Obviously they are smaller tacos but 3 tacos is plenty good for breakfast, just about right.
In terms of ingredients in a taco, Nopal and egg is one of my favorites as is Chicharron en Salsa. Hadn't seen these mentioned.
Back before the prices went up, I could get three tacos and a DP, breakfast of champions mind you, for less than two dollars at Rocha's. They beat the hell out of Stripes.
For quality, value, and selection I doubt that there is a place in Texas, or northern Mexico, that can touch this place.