And then there's the Ercoupe to Alaska.
http://ronkilber.tripod.com/alaska/alaska1.htm
I think what you are seeing is a real down trend in twin engine piston engine airplanes. The cost of a 421 has dropped >30% in the last 2 years. I think maintenance is a large part, but so is the high cost of 100LL. While 421's have seen their market deteriorate, the 425's (Conquest I's) have seen steady or rising prices. They are turbine aircraft. Turbines seem to holding their own, and pistons seem to be losing ground. Look at the difficulties that Adam is going through. No one wants a piston airplane anymore, not when you can get a turbine, have an assured supply of fuel, at reasonable prices.
It's not user fees that will kill general aviaiton, it is the high cost of fuel. Part of the whole FAA funding thing calls for even higher taxes on aviation fuel.
I remember reading the stories of the fly-in at Abacos, and Don Hickman paid $1.85 at one of his fuel stops. We will never see prices like that again. Yet many of us bought planes when that was the reality.