You could use this principle to all brands of high performance models, Porsche's GT2 costs more than 2 times as much as a Carrera C2, the M3 costs twice as much as a 316i, etc, etc, etc, etc.
My real problem with the TT/RS is that they have placed items in the options list that were standard spec on a TT/S. MR should have been standard, as should 19" alloys, both things that would justify it's £10K increase over the TT/S.
Some reviewers are saying that Audi dropped the ball with the entertainment value of it's latest RS model, I don't know about that one but they definitely did on the overall value of what you are actually getting for your dosh. This product should not have commanded the same basic price as a Cayman S. NEVER.
In my mind it's £3k too dear.