Cheapest on staticice by double digits ( http://staticice.com.au/cgi-bin/search.cgi?q=roccat+kulo&spo… )
Mwave site says "very limited stock" and also a limit of 1 per customer.
I don't own one, haven't read reviews and don't have an opinion on how good it is compared to product x, but I would be guessing that at a fairly big discount that it would compare favourably to most other USB headsets at the ~ $50 price point. Google is your friend ;)
ed: looked up 4 of the 6 first google hits for Roccat Kulo review and got a mixed response. Some are happy with sound quality and comfort, others find that sound quality and comfort are lacking. All I did was skim conclusions, but it looks like you'd need to keep in mind that this is an on-ear headset, so if you're not used to it then you may not find the experience to be satisfactory - even for the discounted price.
Heads up courtesy Oppressa from OCAU (original thread: http://forums.overclockers.com.au/showthread.php?t=1018006 )
Ear-cups look uncomfortable.