Welcome, jaydough!
There are lots of threads on the topic (you'll find that if you search Google, with the words "cheap food" and "lthforum", you'll get better results than if you use LTH's search engine), but here's one to get you started.
Great lechon jibarito (a garlicky roast pork sammich made with pressed and fried plantains i/o bread) and probably the best--juiciest, tender-est, flavorful-est--fried chicken I've ever had in Chicago at...
Borinquen
1720 N California Ave/Wabansia
(773) 227-6038