I doubt it'll be significantly cheaper too.besides being electric/sexy/trendy I don't see what the benefit of this is over something like a robinson R44.. which is proven, carries 4 people and has basically the same specs of speed and range that this is aiming for. a new robinson is like $400k right?? I would highly doubt if one of these is made for less.
The difference is in the running cost. A helicopter is a mechanical geek's wet dream, but an accountants nightmare; so much mechanical stuff that moves that it's going to eat up complex expensive parts all the time and maintenance is measured in US$ cubed.
Electric has the potential to reduce this enormously.
I've talked to several owners of electric sailplanes. Most owned 2-stroke self-launchers before and happily paid more for an electric system. Dependent on who you ask, reliability (MTBF) is increased 10 to 100+ fold while running cost are decreased by about the same amount.
As long as battery lifetime (not 1000 but 10^6 charge cycles) can be reasonably solved, I don't see why you can't operate something like the Lilium far below the cost of running a normal car, assuming normal GA price levels for components etc.