I've just moved into a new house with a couple friends in the past couple weeks, and with all hallow's eve coming up in the next few days I thought I'd share my quick and surprisingly nice looking yard display. The biggest key is using materials that are either cheap or easy to come by for free. At most this entire setup cost me 20 dollars.
Step 1: Materials
Ever the dumpster-diver, when I went looking for materials I went poking around behind some local businesses. If it's in the dumpster (skip for the brits) it's free to take. I grabbed a couple shipping pallets, some foam, and a big tangled mess of thin "fish tape" rope.
These alone won't be enough though, so head to your hardware store and grab a couple cans of the cheapest black spray paint you can get, and one can of similarly cheap red. Snag a can of expanding foam as well (great stuff). A box of 2" nails to hold it all together and you're all set.