x-type catalysts

Hi fellow members, I'm new to the forum but 10 years & 3 3.0 x-types into the cars themselves.

My current one is a 21 plate 3.0 v6 sport auto and I find myself in the strange position, for the 1st time,

of requiring a catalytic converter for the second bank, and also finding that they are not available

new in the UK, apparently. Unless, to coin a phrase, you know differently. I would appreciate  

any help in finding a supplier. 

I have found several used ones on the interweb, but putting a used one on for what appears to

be something close to the price of a new one, £150 - £200, seems a poor deal.

Thanks in advance for any help.