There are so many answers to this question, and some of them depend on your definition of "inexpensive."
You're charging $13 a head, and you're not-for-profit. Expensive could be $100 or $1000--depending on the results. But...let's see if we can do it on the cheap.
First and foremost, you have to have RELEVANT CONTENT. Good content means more visitors, other sites will link to you, more links boost your search engine rating. Get linked to HauntFinder.com (right here at HauntWorld), and the International Association of Haunted Attractions (
www.IAHAweb.com).
Make sure you do banner exchanges with your sponsors.
Get a media sponsor.
Also...every bit of advertising that you do MUST GUIDE THE CUSTOMER TO YOUR POINT-OF-PURCHASE, which should be your website.
Your webhost and/or designer should be able to beef up your metatags, but that could result in artificial inflation of your hits. Ultimately, its about the quality and intent of visitors to your site. You'll get hits from "tourists," and you'll never sell them a ticket. What you have to do is make your site totally involving and absolutely irresistible to those most likely to buy tickets.
If I may of further assistance, you have only to...Ask The Dark Lord.
DarkLord@VoiceFromHell.com
www.VoiceFromHell.com