It looks like WOOT sells only one item each day and then it's gone.
From the FAQ on their website:
I missed yesterday's item, can I still get one?
No. Each woot.com product is discontinued at 11:59pm central time. That's that. Period. We may get more at a later date if we're lucky, but we offer no guarantees, we allow no backorders, and we have no waiting/notification lists. Too bad.