DA40NG
Do you operate or own a turbo prop? If so you'll know the statement:
The acquisition cost is only a small amount of what it will cost you to actually operate the aircraft..
applies even more so to turboprops as it does to pistons. With pistons it's in the fuel costs. But buy well and the maintenance should be manageable. With turboprops the maintenance will hurt. Not to mention the cost of acquisition. You state that "avgas is becoming harder to get in Europe". It isn't really so far. Unless you're heading to the back of beyond. It's scarce in the Middle East but I'm assuming the OP doesn't wish to venture this far.
Spamcan I won't try and talk you into a single. You're doing the right thing in researching, there are so many pitfalls.
You mention Cessna cabin class twins. The limited experience I've had of these through other people are that they are expensive to own. A good survey is essential to ascertain what SB's are outstanding etc. Also as they are out of production for so long you may struggle long term with part costs. I'd avoid geared engine variants too.
At that money I'd be in a standard 58 Baron. Rock solid, no big gotchas that I know of, still in production etc etc. 6 seats, though from memory you're only going 200nm or so with adults in all 6. It's a beautiful cabin for 4 pax though. So much space.
I personally wouldn't buy pressurised. The differential on any pressurised piston is so low that it doesn't make a huge amount of difference to your safely achievable levels. I'd be more interested in oxygen.
Glendalegoon, the master of the MU2
is correct. If 6 adults is you're mission more than 10% of the time I'd be considering a whole other set of airplanes, but at three or four times your stated budget.