Uggs are way overpriced.  These boots are the best alternative.  The outside is made of suede and the inside is made of sheepskin.  My feet feel so warm in them, and walking in the cold is no longer torture.

A tip- you should buy spray that puts a "seal" on the suede to keep off moisture and water, in case you decide to walk in the rain or snow. I always spray these boots once per year and I never have issues
Even if you do buy a new set of boots per year, these boots are so inexpensive that it isn't that big of a strain on your wallet.
My last year's boots are still in great shape.  I only bought a new pair because I wanted them in a different color.