When you consider what you get for the costs, the price actually evens out quite a bit. I love local haunts and support them as much as I can, but I still see the draw to a massive haunted event.
8 houses - Even meccas like Netherworld and Bates Motel charge 20-30 bucks for 2-3 haunts. So, they match up at 10 per haunt.
Scarezones - I have yet to be at a haunt with as extensively decorated outdoor areas as a theme park can provide. They do great stuff in their queue's and sometimes even in the parking lot, but for sheer immersion the parks have the obvious advantage.
Rides - If you are so inclined....I don't think local haunts can provide much more than jumpy houses or, occasionally, a traveling carnival ride. They would probably upcharge for those, too.
Please do not think that this is in any way a slight to independent and regional haunts; I love, respect, and envy what they do and would love to join them someday. However, dollar vs dollar, HHN, Knotts, HOS, and the large theme park variety haunted events do provide equal to the costs. If they go much higher, I may not be able to enjoy as much as I'd like, but that is due to my own financial burdens and not the fact that it's a fair or worthy price.