We have some stuff set up in an abandoned warehouse in the middle of nowhere. There was a ton of random stuff to skate/make skateable there when we found it: big metal desks, office chairs, a couple couches, metal pipes, a bunch of plywood, and some weird pvc piping. All it took was some tools, screws, quikrete, and wax and we made a pretty fun little "park" for rainy days.
Everything we have is built with stuff we found. I think we've probably put about 40 bucks total into making the spot.
In your case, actually having that many people to throw down money and put in work, I'm sure you'll end up with a really sick place to skate.
Best advice I can give is to be creative and make stuff you can easily change, rearrange, and stuff that way it never gets boring. Also, bring random shit you find there. We have a 6 stair made with a runway of desks and shipping palettes, with a big metal office desk hubba ledge and a metal couch frame handrail, a kicker over a sketchy old leather couch, some boxes, filing cabinet ledges, a super mellow pole jam made from sticking a metal bar into a hole that was already there, and all sorts of other random shit.