Can you rent a fire hall, church hall or social club? Think inexpensive wedding reception.
For food.....most hoagie/sub shops around here offer 6ft party subs for around 60.00. I'm lucky enough to have 2 shops that offer their regular hoagies, which are 14 in long, for about 6.00. I order 6 or 7 of those for 20 to 30 people, (you may need more), more than 6 ft and cheaper, and cut them each in to 8 pieces. Some hamb BBQ, potato, macaroni and pasta salad. Some nachos/chips and salsa, pretzels and chips and voila, a party that doesn't cost a fortune.
Until you add the DJ.
Which is easily handled by renting a karaoke machine or giving one of the kids DJ duty.
You could rent a big TV from Rent-A-Center (or the hall might have one) and hook up a Wii or whatever.
Good luck!
Almost forgot....Super Walmart has huge hoagies really cheap!