There will be plenty of tickets available in the month before the ride. Right now everyone still thinks they can catch up on their training.
That said, I am also looking for a ticket.
If you don't get into the Death Ride or an epic ride later in the summer fits your schedule better, consider the "tourist" division of the Everest Challenge (there is also a race, which is what most people do). The climbs are bigger, the ride support is better and so is the scenery. And there's only a few hundred riders instead of 3000.