Before suggesting not to buy headphones from amazon.co.uk and recommend other dealers you should consider the location of the buyers and that amazon.co.uk offers the shipping costs for most products.
None of the sellers you recommended ships from the EU which means extra shipping time, and extra, unpredictable, customs fees.
K550 for 130£
DT880 for 299£
Both shipping included from amazon.co.uk
Please let me know where you can find them cheaper in Europe.
PS: Also interested in Sennheiser HD600
Shipping fees are included from Razordogaudio normally... and no custum fees either. I don't see the problem there...