It's actually a good strategy to price high hourly but over-deliver (doing lots of free work behind the scenes, or speculative unpaid work, etc.) -- rather than the market-clearing rate of ~100-150/hr, at least when you're trying to build a brand. At $400, he's clearly a specialist, and will get more interesting work; at $100/hr, you could hire him and just treat him like another developer, have him do cookie-cutter assessments, etc.
Personally, I think he'd make more money at $400-600/hr if he could also get some kind of manager to handle the interactions with clients; it doesn't seem to be what he enjoys, or is particularly good at.
(I've had drinks with him before, so probably the most effective way to accomplish my goal is to buy him drinks when I'm in town.)
