IO540
The O&N Aircraft Cessna P210 turbine conversion fits the bill. Allison C17 turbo prop.
205kts/FL200 25gph. 4 hour range with 4 occupants. 5+ with two occupants.
Less than a million $
Full refurbish, Garmin 600 glass cockpit.
Operates happily off 700 metre grass strip here in Berks.