If you were to do a survey you would probably find that the amount a rich owner is prepared to pay will likely be the same for a normal owner, possibly even less. Rich guys don't get rich by splashing cash on money gouging mechanics in any industry and aviation is no different.
A friend used to be Lloyd Williams gardner and if he was to get a small plumbing job done for example, Lloyd would always request that he got 3 separate quotes before authorizing the work to begin.
I know people with a $150,000 aircraft that wouldn't cough up $60 to buy a ticket to go to Avalon.