I know there are quite a few joints in Pilsen with $1.99 breakfasts. Never had one, though. Try El Vaquero at 18th and Damen, which opens at 5.
Speaking of El Vaquero, I actually finally tried it the other day (mostly because it's a half-block from home). The offerings ranged from fair to quite nice. The best of the four tacos (cecina, carne asada, pastor, and some other type) was definitely the pastor, which was caramelized and crispy and had great spice. Mind you, I'm not sure it was off a spit, but it was still rather good. Flautas were merely adequate. Table salsa rojo was nice, and the chips were, at least then, fresh.
This is all based on one report, so who knows.