Nice one! That's a really good response and one to be filed away for future use.
As I read through he thread, the predominant thought was that if the customer can go to all the trouble of setting up a kitchen shop, he must have had a plan that was more solid than what he is making out.
I hate it when people try to weedle down prices, and I end-up thinking "How much does the garage charge to service your BMW? Can you steamroller the garage on prices?".
Your final decision sounds like the best way forward.