I am sooo disappointed in all of you. This is what the internet was created for, isn't it? Better shopping choices?!
In a couple minutes I found a huge variety of what I would call suitable costumes for children who are not yet teens.
Take a close look at these costumes - this one, a fisherman - could be put together basically from things in your own home. Just think creatively.
and, there is also the "t-shirt" costume. Here are some possibilities along with some fun bags to use for holding treats when trick or treating.