I bought these from Underwood Hi Fi last May, for a total of £500 including the Customs charges. They have an agreement with Kennerton whereby they can effectively sell Kennerton's headphones with their own finish and branding. This is taken from their website:

The HP-3 Nova is our version of the famous Kennerton Magni. It is identical to their current version 3 with our cosmetic twist. The Magni has received many great reviews at its $800.00 price. The Magni and our HP-3 Nova use a hybrid driver of mylar and powdered graphene applied by a thermal bonding method.

They have had very little use indeed since I bought them, no more than a few hours. I just don't get time to listen to music through headphones any more.