Aladdin's takes plastic and has for a while now. They prefer cash and if you have cash and in your wallet and hand them a card they will point at the cash, but they'll take plastic. Also; damn tasty. Go there often.
Ok, for Mexican food on Capitol Hill the only reasonable choice is Tacos Chukis. And it's cheap or cheaper than anything you've listed. Also, why not a shout out to one of the cheapest lunches in the city: a fuckin' bahn mi?