Asanve, another thing you can try is asking your local chamber of commerce. In a small area such as yours, they will often know of previous charity haunts. Then, if there were such haunts, you could go to them and ask what kind of attendance they experienced.
If they ask why you want to know, be honest. (You know how small towns are; you don't want a bad reputation.) It might worry them that their haunt may suffer if you open one up, so you might want to think through what you will say in that case.
You might also consider using a MySpace page to reach your target market and ask them questions.
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