Just bought a pair from local auto factors about £30 each.

but try http://cgi.ebay.co.uk/PAIR-MORGAN-4-4-PLUS-4-PLUS-8-BRAKE-WHEEL-CYLINDERS-/360157041540

or Delphi LW15953. or Caparo AP Braking CW 15953.

I am sure I got info from another thread on this site!

Hope this helps