Sin Fronteras has good quality and variety, and is very well priced.  A burrito with your choice of meats is only 3.99 ala carte.  Lots of meat, no rice or beans.  Very tasty and authentic, with your choice of salsas including a terrific homemade salsa diable (very hot).  Also tacos, gorditas, tortas (sandwiches) and sides.  All this from a small restaurant that is part of a hispanic supermarket.  The owner is often the cook.  Well worth a visit.