I can speak to this from personal experience. I fly the Piper Arrow and have rented from various FBO's on both coasts in various economic areas over the years. The average price I pay per hour is $145 an hour wet. All of the Arrows I have flown have been similarly equipped and of a similar vintage. They have all had at least a single axis auto pilot a 430W and are in fairly decent shape.
The cost really depends on your mission. If I'm just flying the local area with some friends its far more likely I (and many others like me) will fly an Archer which holds the same number of people as the Arrow and is about 25Kts slower. The average price I have paid for an Archer over the years is $119 an hour wet. All of the FBO's I have ever rented from have had both Archers and Arrows (or Warriors) available and if you are checked out in the Arrow most places will let you fly the Archer (slower and non retractable) without an extra checkout.
The Arrow tends to be a "go places" airplane so the flights are a bit longer which will cost you more on a day to day basis but less on a per mile basis (the Arrow is more efficient).
My average \$100 hamburger mission (hey that's me) ends up costing about $225 when all is said and done. If you want to keep it right at \$100 see my answer here. There are lots of great little trips from my home base that are under an hour but with taxi, IFR clearance if I need it, routing, a denied bravo clearance, the scenic way home, or just letting my buddy take the controls for a bit it ends up taking just about an hour of Hobbs time for each leg.