Most of the past TuneBoy group buys have been organized by a member of one of the D675 forums. Usually they are held each Spring. Right now, the USD/AUD conversion is not very favorable - the US Dollar is low. But you might find a TuneBoy dealer that has several kits purchased before the US Dollar dropped.
Right now direct from TuneBoy they are ~USD $450 and British Customs has the kit listed for $450, while newSpeed3/newbonneville has it listed for $400.
http://www.newspeed3.com/html/tuneboy.html
I hope this helps.