The way it works for me is, around $88 an hour with fuel for a C172, and you are charged for only the time the engine is running (time on the Hobbes) and if you take it for more than 24 hours, you are charged a minimum of 2 hours, even if you fly for 10 minutes. Might be different where you are though
That's almost exactly what it is at my club for a 172. And it's pretty reasonable. It's based on 7-8 gallons per hour of fuel ($3.50/gal)... $7.00/hour for the engine-wear ( HAS to be replaced every 2000 hours on planes for hire @ $14,000)... $7.00/hour for maintenance... plus insurance, tie-down, use of the plane and a small profit for the owner gracious enough to lease it to the club.
It's an expensive way to kill an afternoon, but not all that expensive a way to travel.
Example: Two adults can fly from Columbus, Ohio to Chicago and back using about 5 hours on the Hobbes.. about $480 wth tax. That's $240 per person round trip on YOUR OWN schedule and no security lines. Considering you need to be AT the airport two hours before departure... you'd be entering the pattern in Chicago to land by the time you were allowed ON the commercial flight. ;)