Re:Street taco meat
Do you mean steak or ground beef? Big difference.
Depends on the shell size of the taco you're gonna sell. Bigger shell, more meat.
Soft or hard shell, Corn or Flour?
Suggest you decide the size and style you're gonna sell and experiment with it until it until you get it the way you want to serve it and then price accordingly. If you have a good price/value taco that tastes good, people will buy it.
Personally, I prefer soft flour tacos as opposed to hard corn tacos. Easier to handle and eat as stand up and eat street food.