Hello again and welcome to yet another thread where I show you how I've scared a bunch of little kids with pocket change.
Let's say you have a few dollars, some masks, but few volunteers. Is your haunt going to be empty? Heck no! All you need to do is go buy some lengths of 1x2 wood (I found it to be about $2.50 for 8' lengths), fashion them together into a simple triangle, nail horizontal boards on for shoulders, waist support, and feet, and put a diagonal piece connecting the foot and vertical pieces for support. I found that for wood that small, a couple smaller nails at each juncture along with some duct or packing tape held through the life of the haunt.
If that didn't break the bank, march yourself over to your favorite dollar store and buy whatever color of plastic tablecloth looks the scariest. Toss a latex mask on top (I'm sure you have one lying around!) and you have a large, scary, giant figure!