I have found another couple of cheap oil pumps from nissan in America, I think it's £10 more for the postage but the pump is the same price
Heres the link if it's any use to anybody
http://www.ebay.co.uk/itm/Nissan-Pulsar-GTi-R-GTiR-SR20DET-Front-Timing-Cover-Oil-Pump-Assembly-/181329772680?pt=Motors_Car_Truck_Parts_Accessories&hash=item2a3818c088
Heres the link if it's any use to anybody
http://www.ebay.co.uk/itm/Nissan-Pulsar-GTi-R-GTiR-SR20DET-Front-Timing-Cover-Oil-Pump-Assembly-/181329772680?pt=Motors_Car_Truck_Parts_Accessories&hash=item2a3818c088