In reply to phja: I just bought a 77mm polariser off ebay UK for a very reasonable price.
Slim 77mm Circular Polarising Filter Polarizer UK CPL Kenko Pro1 D Hoya B&W
Super Slim 100% Genuine UK Seller Canon Nikon Sony
Item condition: Brand New
Time left: 23d 18h (04 Apr, 201304:17:06 AEDST)
Price: GBP 25.00Approximately AU $36.49