If your hotel will give you some space to cater in a meal, I'd highly recommend Bella Italia in Ann Arbor. Their catering menu with giant trays of pasta is very inexpensive per person, everything is made from scratch, and they might even deliver to you (I know they deliver around Ann Arbor). Even if they don't deliver, someone can drive a few miles out of the way to get it and throw the trays of pasta in your trunk. The garlic knot rolls are cheap, filling, and kids love them. I regularly feed 80 kids on field trips from them for amazingly little money.
Not between EMU and Milan, but still in Ypsi is junk food heaven--Bill's Drive in. For about $5 you can get a couple hot dogs, a bag of chips, and THE best homemade rootbeer. That's all they serve, but they'd get it done fast and tasty.
Just off US23 is Great Lakes Chinese Restaurant. They have a large private dining room. We worked with them to get a reasonably priced, kid-friendly menu for a big group once. I can't remember what they charged, but it seems like it was under $10 a kid with tip. If you'd be dining at kind of an off time, I'm guessing they'd work something out for your group.
Do you have 5 Guys Burgers and Fries in your area? All the kids love the place (but if you have peanut allergies in your group, know that there are in-shell peanuts free to grab in the dining area).
There's one at Arborland Mall, on Washtenaw right across from where you'd get on US-23 from EMU.
3601 Washtenaw Avenue
Ann Arbor, MI 48104
I'm not familiar with Milan at all so I can help with things closer to your hotel.