Knock Sensor supplier in UK?

[Mike_Buckham at ptk.pioneer.co.uk]

Hi,

I've finally discovered that the apparently intermittent fault in my engine
is that the knock sensor is faulty - it seems to be over-sensitive at times
and forces the ECU to retard the ignition when it shouldn't and causes very
bad running and poor idling. I tried making a cardboard washer between the
knock sensor and the engine block, but even this left it too sensitive.
Finally, I made a bracket to fix the knock sensor onto which absorbs a lot
of the vibration. With this in place, the engine runs properly. So now I
want a new knock sensor. The local Audi dealership tells me that they cost
about 85 quid each. Does anyone know where I can get a cheaper one in the
UK (new, not used)?

Cheers, Mike.
1989 200qt Avant (1B engine)