The only criteria are as follows:
Some kind of bathroom (latrine would be tolerable)
tent site, we don't need electricity
Near central PA
Most of the places I am finding online are like $30+ a night and a lot extra for that fifth person. We're camping from Aug 20th through Aug 23rd.
We don't really need a big commercial campground, but I don't know how to find a small, rural, cheap place to put up a tent or two.