Chick-fil-A and the Dragon's Inn concession next to Iron Dragon have always been my favorite "bang for your buck" food stalls at CP. In the end though, you are paying way higher for in park food.
Therefore, if dining for cheap is a priority, I recommend heading back to your car, leaving CP, and driving out for a regular priced restaurant. You are allowed one re-entry with paid parking (Platinum Passes have unlimited parking), so you needn't worry about having to pay when trying to park again. For instance there is a McDonalds at the beginning of the causeway, only a matter of minutes from the parking. Driving a bit further to router 250 (the main commercial strip) will lead you to any number of fast food options (now including Chipotle!). Once you're done eating, simply head back to the park!
This is a trick I have used at numerous theme parks, and it usually works fairly well!