Online Travel Booking and Bidding Agencies - Cheap 'D' Class SQ ticket LHR-SIN-SYD in Oct?

I'm looking for a pair of cheap tickets in Business (Hence my desire of a 'D' Fare) in SQ for LHR-SIN-SYD and back, this October.

If this isn't available a grey market biz ticket, or a SQ ticket from another european hub would be considered.

Thanks.
Regards,
Alex

Flying ARN-LHR-SIN-SYD with SK/SQ is 31737SEK(3493EUR) in C class.