Hi,
I replaced my AP Racing discs and pads recently for the 6 pot kit i have on my classic.
Best price i got after checking with loads of suppliers was Circuit Supplies Ltd - http://www.circuitsupplies.com/
Discs where AP 355mm and pads where Ferodo DS2500. Also got a set of the nuts and bolts for each disc. No one got anywhere near them on price. Fist class service aswell.
£485 Delivered to the door.
Hope that helps.
Baz