Not a great deal of price difference between a new Lyco 4 & 6 cylinder engine - I would guess $7-10K. Component costs and installation (during manufacture) time would not necessarily cost more than manual system.
So why the much higher purchase price?
I would say the extra liability premium for 2 extra seats would be the main factor.
To list but a few - insurance risk increase by # pax.
Robinson Helicopter Company in Torrance subject of wrongful death lawsuit
https://www.baumhedlundlaw.com/fatal...helicopter-co/