I went this weekend and was pleasantly surprised. They have Mexican Coca Cola (which is made with sugar cane) which was a fun touch.
I had the Enchiladas Rojas which were quite tasty despite being made with Chicken, which was very tender.
As others have said, this place is easier if you can Hablar the Espanol (I can't, so "no aguacate" somehow turned out to be extra avocado...)
I'm not done looking for THE really good, really cheap Mexican place in Charlotte, but at least I have a solid contender.