Don't know if you've found any yet but here are my best suggestions:
UGG Outlet Store
Gilt.com
RueLaLa.com
Hautelook.com
Bluefly.com
Zappos.com
Nordstrom Rack
Century 21
Saks Off Fifth (the outlet store one)
Macys Outlet store if you're in NJ/NY
DSW
Those places are where I've seen discounted Uggs before, at worst you're looking at 20% off or so, best around 30-50 depending on the store, style, etc.