Unfortunately the OP has been removed from AB along with her posts and subsequent answers - but to continue the chat I think you said something like " Why are not scrap yards recovering the Pt". If you ask most people whats in a cat they will say Platinum.
That's why most adverts are for Pt.
Because of the high value of the metals used within them, maybe still the highest value (£) to weight ratio component in a new vehicle. A 3 way cat converter containing Platinum, Palladium and Rhodium, it is worth recovering the Pt, Pd and Rh, hence scrapyards will remove them and sell them them on.
You can remove all the metals within a facility set up to do it commercially - just a matter of scale - a bit like gold mining.
Your thoughts about ebay maybe true but why will this scapyard buy them?
http://www.ukmetalrecyclingltd.co.uk/
Await your thoughts