I heard on the radio the other day that apparently Ugg are quite serious about cracking down on fakes and work with customs to spot them, and they will get destroyed if spotted. And all websites with "ugg" in the name apart from the official one will be selling fakes.
I would not buy from that site. Their shipping terms and conditions are appalling. Also, there is no telephone number or address to contact them at all. They are most likely based in China or something like that.
If you're not fussed about having the real deal, why not buy a pair of sheepskin ones that are not branded as Uggs? Or buy a cheapo pair that are not sheepskin?
I have a pair of unbranded ones from a local shoe shop and they are really comfy, look great and have lasted a year so far. They cost me £25. You don't need the real thing or a rip off of them. Go to primark or something!