I don't think you can even get a (new) 10 seat plane for less than $10,000,000. And I doubt that a plane built using technology that doesn't exist yet will be 70% cheaper than ones you can get today. Even if you can find 33,000 planes for that cost there will be significant infrastructure costs (if you want to multiply the # of planes in the air in California by 10, you'll need more ATC, more runways, more hangars, more parking garages, and probably more airports).
Upfront costs are just a small fraction of the price of flying planes around. That 3 (or 10) million per plane quickly gets subsumed by maintenance, staffing, and other recurring costs.
I don't know how loud these hypothetical electric planes are, but if they're like traditional ones I doubt that they'd beat a train in terms of noise (even though HSR can be 10-20 decibels louder than slower trains). I would question that there would actually be an advantage in speed or convenience, at least between highly populated areas.