Los Altos Tacqueria II in Concord
Had lunch there this weekend during an outing to Fry's. Had three regular tacos ($1.55/cilantro, onions, salsa) -- al pastor, carne asada and chorizo. All were good and authentic. Also tried their pork tamales, which were good too. Fairly extensive menu, free chips/salsa bar, and reasonable/low prices. Not necessarily worth a special trip, but good to know about if you're in the area. In the strip mall in front of Fry's (where The Mediterranean is located). 1747 Willow Pass Rd., Concord.
Went to Los Altos last week as I was in the area to buy some furniture.Had two chicken enchiladas asked for green sauce instead of the traditional red, refied beans, rice and 2 tacos, one chicken, and one carne asada.The enchiladas sauce was great, the beans were buttery and creamy, the salsa on display was also very good. Prices are also very good for what you get. Overall a very nice lunch. Agree with the earlier post, not necessarily the place to make a special trip too but if you are in the area definitely worth checking out.
Funny - I had a chile verde chicken burrito here last week myself. I liked the beans, but the meat content was a bit sparse and was average-tasting at best.
Also, if you're not a fan of chips kept under a heat lamp, this isn't your place. With that said, the chips weren't bad and the salsas were decent. Prices were on the lower side of things like the OP mentioned.
Not a destination place, but it's decent enough if you're in the mood for Mexican and in the area.