Looks like the Halloween and Christmas parties are very popular this year. The advance sales prices are no longer available for certain dates. This does not mean the dates are sold out, this just means that the full gate price applies for anyone booking these dates forward.
The dates that no longer offer advance purchase savings are below (this also includes dates that didn't have it and are not sold out yet):
Not-So-Scary: 10/8, 10/22, 10/28, 10/29, and 10/31
Very Merry Christmas: 12/7, 12/10, 12/12, 12/17, 12/19
This means if you haven't booked your tickets yet, I would seriously think about it. Most of these dates are getting close to sellout, especially the ones near their respective holiday.
The dates that no longer offer advance purchase savings are below (this also includes dates that didn't have it and are not sold out yet):
Not-So-Scary: 10/8, 10/22, 10/28, 10/29, and 10/31
Very Merry Christmas: 12/7, 12/10, 12/12, 12/17, 12/19
This means if you haven't booked your tickets yet, I would seriously think about it. Most of these dates are getting close to sellout, especially the ones near their respective holiday.