UK - Catalyst for 2.8 A6Q

Had my 1999 A6 Quattro from new, done 110k miles, never had anything go
wrong with it.

Noticed the exhaust sounded like it was "blown" especially on start up.
Took it to a local exhaust place and they told me that its not leaking, but
the passenger side (UK car) catalyst had broken up and was rattling inside
the cat box.

They had to ring around to get a quote for replacement. Best price was £550
including fitting (close to $900)

Anyone able to recommend where to source one any cheaper!! New or would
consider one from a breaker.

Reply to group please.

TIA

John.