As previously hinted at, in Australia and New Zealand sheepskin boots (which have been around down here for decades) are known as ugg boots - we do not differentiate by brand. There just happens to be a brand called UGG but there is little difference between these and other New Zealand/Australian made sheepskin boots - save for the label on the back of the heel!!! For some reason the UGG brand has become a household name outside of Australasia and thus the great demand for them.
If you don't want to wait until April of this year for UGG stock and are looking for a comfortable sheepskin ugg boot in tan or walnut (baby pink/baby blue coming soon) check out:::
http://www.miwoolies.com
Ugg boots for men and women are available - a great range of styles in varying heights with a choice of sole, lace-up ugg boots, ugg boots with possum-fur trim.
Prices are extremely reasonable - around $US70 for the shortest boot.
Hope this helps!