No better off Rob. I have a used set from Japan which I took a gamble on & it's the same story. Adding to that, the amount of time I spend browsing Yahoo JP I've rarely come across seat belts being auctioned, unless you find a soarer being wrecked & in the same colour trim.
IMO, as a temporary measure find yourself a good known working replacement & if serious about a solution get in contact with: http://seatbeltsolutions.com.au/