I strongly suggest you don't buy a car seing as then it's yours after the demo, best bet is go to the scrappy and ask how much you can borrow 2 or 3 cars for if he can drop em off and pick em up, then tell the shop owner how much, same with a skip but when you ask for it ask if they can tip it, then nick some pallets with someone with a pickup, reel from BT, some wood to mail around to make thin, high walkways....Be inventive by all means but its likely the crowd will be impressed with you hopping on the back wheel, so don't build a castle.