I know this might not be what you are thinking of Locky but
Wouldn't something like a disused airfield with a couple of hangers toilets etc be a good sort of place for something like this or a large warehouse
My thinking is it would be cheap
We couldn't do much damage
And normaly places like that have some interesting obstacles
We could also get a few stage type platforms
The insurance for a place like that would probably be lower
Would be a bit different industrial setting for good pics
As for transport hire a mini bus to bring people from the local station for a small fee (enough to cover the bus and driver hire)
Unless you are looking for large crowds in which case you are stuck with the expensive venues
Jason