I have heard when Macy's does their annual friends/family days discounts, that is good time to get UGGs.
What we did last year when we bought some for our DD, a local sporting goods store had a Black Friday coupon for 20% off a $100 purchase. So - you may want to keep an eye out for something like that too!
Another thing to consider - does your school do SCRIP? If so - while it wouldn't give you a discount on UGGs, if you bought SCRIP for Macy's - they amount your organization would recieve is around 8 or 10%.