No! I'm guessing...
But, they are the ones that are selling them off through eBay. I'm sure if you walked into your friendly local BMW stealer and asked for a new radiator, they would probably charge you the full retail price which from memory was about £600. Rae was the last person who I know of who was forced to buy one so he can confirm the cost.
When I was trying to match some tiles from B&Q, the only place that had any was one of the Bristol stores. I rushed over and bought the entire stock and when I asked why they had them and no-one else did, they surmised that head office had sent all the existing stock from other stores to them to dispose of; they were massively discounted when I bought them.
So, perhaps the same thing is happening with the K rads. Either way, I'm now doubly insured...and desperately trying to stick a load of white tiles to the bodywork