When I bought my TR about 5 years ago I looked at a few M's as well, they were 25-30% more. Haven't seen one for sale for a while now. From memory there were only about 41 sold in the UK, just under half as many as the TR.
Tom Hartley Jnr has one that I found out about, spoke to him today about it and he wants 250k even though it's not for sale....apparently. There is one in Aus that is lovely, but after VAT it'll be near 200k. I don't think they are worth that, or rather I wouldn't pay that.