Today is the last day for the $30 rate, tomorrow it goes to $45. Also, there is a limit of 500 people, there are now 347 registered. When I posted this up a week ago, they only had about 170 registered.
Also, you cannot just show up the day of the rally. It's on a military installation, they need a list of attendees before the rally. Iff'n you're not on the list, you will not be allowed in.