We lived on a farm in Australia when we first got married and lived in Ugg boots (usually bought for $20 in Big W!)
I wanted to buy my husband a pair for Christmas this year and ended up ordering them from the Celtic Sheepskin Company on the Internet. They weren't cheap but they were excellent quality. The order form gives you advice on what size to order, I think. They're not the original Ugg Boots brand but my husband says they are every bit as good - and he should know being the son of a sheep farmer!They do loads of different colours as well.