where do people get them fancy red clutches from?

Southbend ! They use Sachs pp and clutch plates only re-lined with their special friction materials and add their custom harmonical tuned Single Mass Flywheels so the chatter at iddle is nil !
 
Unfortunatelly they don't do kits for 8E audi a4 b6 as that wasn't sold in the states with a diesel engine ! You will have to use a 1.8T flywheel but it's not guaranteed to be vibration free as it's made for a petrol engine which has different harmonics. I used a Southbend clutch and TTV flywheel drilled to fit the 4 pot crank, the clutch was a reinforced rs4 jobbie and the flywheel gave chatter and subseqvently the gearbox broke ! The syncro on 3rd gave up after a proper tune for the BV43 turbo was uploaded then the box locked in first a few weeks after ! In the process of swapping a v6 tdi 6 speed gearbox and matching propshaft + rear subframe and diff...
 
I was on darkside devolopments last ngt. Look under transmission!
They do a load of clutches for the a4 tdi
 
Also don't be fooled by some people selling normal clutches just painted red.
Seen a couple of fabia vrs boys get stung with that.