It kind of depends how far from the ICC area you are willing to go. IMO, there are not really that many exciting food options immediately in the ICC/connected hotel area. Lots of chains -not that there's anything wrong with chains- and it's very much a steak n' seafood kind of downtown for the nicer places. I am personally not a fan of the food trucks due to the lines and I don't think they are the greatest value even though they're not super-expensive, per se (you can get more food, free water, and AC for the same price at, say, PF Changs or similar depending on what you order if you're thinking cost-effectiveness only), but they do have a good variety, are right there, and are not excessively costly per-meal depending on what you eat.
One reasonable place dinner right downtown that I do like is Napolese Pizza; very fresh Neopolitan style pizza with good toppings. I think they are open for lunch and dinner weekdays, but only dinner on the weekends. The same group that owns Napolese owns Cafe Patachou downtown, which has a good breakfast, but you won't get out of there for <$10 with tip unless you literally just get oatmeal or toast. Honestly, you will probably not find breakfast for less than $10 in that part of downtown except for fast food and Steak n Shake. St. Elmo's is worth a visit ($$$$$), even if you just have drinks in the lounge.
However, if you are staying or willing to go further afield, there are more options. A mile or so southwest of downtown you can get fresh pastries and breads at Amelia's Bakery for a very good <$10 breakfast. Bluebeard is right next to Amelia's too- I've never been there but they've gotten huge buzz. For lunch/dinner there's also Rook (Filipino fusion), Kuma's Corner (burgers), and 3 Carrots (vegetarian). If you want to use your larger budget on brunch, Milktooth is in that area too- I went there last year and while I didn't really think it lived up to all the hype I had heard about it, the food was good (service not so much). There's also a bunch of restaurants Northwest up Massachusetts Ave, but I have not explored that area as much.
EDIT: I forgot this initially since I take it for granted, but avoid the food in the Convention Center. It may keep body and soul together, but is, in general, not good and overpriced.