Amazon UK has the Sennheiser HD650, their high-end audiophile reference headphones, for a rather low cost of £179.99. Not bad considering it is being sold for US$500 across the pond. The relatively low price is likely due to the pending arrival of the new top of the line HD800 headphones.
The HD650 is an open, dynamic headphone and is based on the award winning HD600 headphones with improved materials for "better sound reproduction". It comes with a standard two year warranty.