There is food sold upstairs in the convention center.
I don't know/remember names of restaurants in the area, but did see a couple on our walk from our hotel. We also ate in the hotel restaurant, shared a sandwich and each had soup/salad. To me, when traveling and wanting to have a budget, you have to think outside the box. Sharing meals, to me is the way to go. Order a large salad and an couple entrees and share between all of you. But, then again, it all depends on the size of your appetite.
I would contact the super shuttle for transportation back and forth, I think the taxi might be more, but you could also call the companies and see what they offer.