What nobody has mentioned is that RB does have an excellent track record for after-sales support. In addition to that, he knows the Omega and all of its' foibles. Having worked on a few cars that have come through his hands, I know that they are sold with all the usual niggles fixed. I also know from those who have purchased from him that he's willing to rectify any post-sale niggles without quibble.
It costs him money to provide that sort of service where most 2nd hand car dealers would tart a car up with minimum expense and move it on, then start ducking and diving if the customer has problems.
Yet we compare his prices to cars sold on here or ebay, where there's no comeback whatsoever.

Would I pay the premium and buy a car from him? Not sure. TBH, membership here means that any potential Omega problem is rendered insignificant by the knowledge available, but, for other buyers, that premium might be worth paying. If he weren't selling them he wouldn't pay to advertise them, after all.