Review thread here: http://www.head-fi.org/t/735024/ultrasone-new-performance-se…
Ultrasone models vary greatly in price, these sell for around $300US in America (Amazon, etc). Not available from many sellers and don't appear to be cheap elsewhere locally or OS.
The reviews (very few) and HeadFi discussion thread are promising on the series and the 840 in particular for the coin and a sound signature that is appealing to me (bassy but otherwise detailed).
Othe Ultrasones on sale;
HFI 450 $99
HFI 580 $139
HFI 680 $169
HFI 780 $189
DJ1 $149
DJ1 Pro $179
Performance 880 $329
Pro 2900 $339
Pro 550 $179
Pro 900 $339
Pro 550 $179
Signature DJ $749
Signature Pro $999
Edition 8 Palladium $1249
Editin 8 LE $1399
Editin 10 $2049
Editin 12 $1249
Choosing not to list RRP as I don't know how accurate they would be.
What a fantastic waste of money right there.
A $219 dollar gamble on a completely obscure brand with very little chatter on the Internet about it; or pay less for something guaranteed to sound good.