You remember the old line about if you have to ask you can't afford it?

Purchase price, hangar (if you buy an warbird you'll want to hangar it), insurance, annual inspection, miscellaneous minor repairs, putting a bit away for major repairs (like engine overhauls) and then the everyday costs of flying it (gas and oil) all combine to make impressive totals. The more horsepower, generally, the more all of these things cost you.
And then there's those urges to "improve" your airplane like getting original bits and pieces to restore it back to "the way it really was".