anic:$22,500 a year for one airplane, fixed costs (parking/hanger & insurance) can't be that much, your mech must have a sweet deal or your bank is raping you on interest. I'd be requesting an audit of your accounts to see where the money is going if your paying that much for a single 172. That or start having maintenance days where members comes in and help in owner assisted annuals and preventive maintenance. If your IA doesn't allow owner assist, find one that will.
Using his costs. If "you" fly it 100 hours a year (most people don't) that works out to about $85.00 per flight hour, 50 hours $100, 25 hours $130 (125 X 12 \ hours flown)+$70hr = hourly cost.
You have to ask, can I rent for less per hour, how much do you fly, what is your mission(do I need or want to have it available to fly immediately), what is the condition of your airplane, fixed costs (hanger/parking/ins/loan payment), and the relationship you have with your A&P all factored into it.
Ownership of an airplane can be expensive on a per hour rate, especially if you don't fly it on a regular basis, cost is relative though, have you checked how much it costs "per hour used" to own a nice boat nowadays.
When I owned my Cherokee 235 my fixed costs (parking/Ins/payment) per year were about 10K, annual (owner assisted) was $300 (less parts) I did my own preventive maintenance,(under supervision of my A&P IA) and I had a relatively low time engine so I figured in about $50 hr for overhaul. My work covered a lot of the fuel/oil costs so that was a little harder to figure.
Currently I own a C150 and live in an airport community with my hanger in my back yard. The airplane is paid for, my partner is an A&P and the IA lives two hangers north of me, so my costs are about $1800 a year (including annual, parts, upgrades and Insurance) Fuel is extra of course