Not wishing to try and teach anybody about sucking eggs, but it seems you need to go back to basics. Many cases of brake judder are, as already stated, due to wheel balance problems. The discs need a certain amount of runout to knock the pads back, so dont instantly blame the discs. Look good and hard at what you've got, changing the discs is obviously only masking the real cause. Drive the car yourself and feel for any wheel balance problems as a starter. I hope this doesnt sound like I'm trying to tell you your job, but we've all been their and sometimes missed the obvious. Andy