They have reserved and general admission. Last year I -think- the reserved went for $60 which gave you better seats and was good for the entire tourney. I seem to remember the general admission was $10/day.
I looked, and I'm sure you have as well and I didn't anything about advanced ordering general admission tickets. You can pre-order VIP seating.
The last four years we have went, I do no recall seeing any type of will-call booth.
Hope this helps...