The words from his own mouth raise far more questions about costs - all his R and D is in house and so is all his manufacturing, that is expensive, very expensive with all the machines, tooling, facilities etc.
You need a big expensive autoclave just to make the fuselage parts let alone anything else.
Making his own engine using 'vast experience of the automotive trade' doesn't inspire confidence either - how many cars have gas turbines?
I'm sorry but I think this is a front-loaded con and I will be surprised if anyone gets what they have signed up for. Very happy to be proved wrong but I won't hold my breath.