This costume takes about 10 minutes and about $2.50. I went to the thrift store and bought a pair of jeans that were large enough to fit over another pair of pants and I bought a army-ish jacket. They each cost me $1.25. The condition of the clothes as far as tears really doesn't matter when you buy them, and being a little worn out is actually good. I used a pair of scissors to liberally shred the clothes, enough so there were lots of holes but not enough it would fall off as the kids ran around playing.
Then I rubbed black and brown crayons all over the shirt and pants to give them a dirty look. We added a little blood with Halloween makeup to the front but that part is really optional. For his hair I filled it with hairspray and ratted it up a bunch. His eyes have just a little black Halloween makeup crayon and that's it. And in 10 minutes and for next to no money it's now a child's zombie costume.
This was the picture the kids took right as they were headed off to school. A zombie, a kitty, and a viking .