There are a LOT of variables that go into that. Age and type of aircraft, availability of parts, etc.
Some folks use 10% the value of the aircraft for Mx which gets you pretty close in most cases of airplanes. Hangar storage varies widely throughout the country depending on where you live, hangar availability, ramp/tiedown space and even more things. Insurance is another hurdle, engine overhaul and propeller overhaul reserves.
If you pay $50,000 for a 172 the 10% rule would mean budget $5000 on maintenance costs throughout the year for unforseen, annual and 100 hour inspections if you do them (a good idea). Some times you'll come in under others you'll go over...
Leaseback of a trainer to a flight school is a popular option to help offset the costs of ownership however the airplane will get "beat up" more than it would if you, the owner, were the only one to fly it.
AOPA has many resources to help you with this. There are many here who will be happy to help as well but that's not their primary dealing. Good luck getting your airplane and remember...if it float's, flys or fornicates it's going to be cheaper to rent
