We charge (wet) 79/hr for C-172's or the Cherokee 180, and 35/hr for CFI's.
This is about the average rate right now, but a lot depends on the fuel prices at the airport you choose to fly out of. We could easily knock off 5-10 bucks from the rental rates if the FBO's weren't charging us 3/bucks a gallons for fuel, and that's with a discount. Transients are paying $4 per gallon.
Remember your average trainer will burn 5-10 gallons per hour, that's usually gonna be at least 1/3 of your cost for a wet rental.