The biggest problem is maintenance. Find a bird that is equipped with
the equipment you will be happy with. Upgrading is expensive and you
won't get your money back when you sell. Corrosion is the main issue to
watch out for in an older plane. Make SURE you do at least one
(preferrably two) compression tests as that tells you the condition of
the engine. Hire a mechanic to do a compression test and research the
AD's and look for corrosion. You should be able to eyeball the paint,
upholstry, glass and avionics. Call an insurance broker and AVEMCO to
get two quotes on insurance. Ask around about hangars, they can be hard
to find, though most eventually find them. Costwise, an IFR 182 will
breakdown like this
Annual $1500
Hangar $varies
Insurance $varies but $1500 a year or so

Hourly
Fuel $40 (yikes its gone up)
Oil $2
Maintenance $varies but $15-25 or so
Engine, prop reserve $15 (you will get hit with this eventually)

Plane ownership is a hassle. Biggest problem is finding a good mechanic
that won't miss stuff but yet won't gouge you. The more involved you
are, the better it is, but different owners do it differently.
Everything from drop it off with the keys and pick it up without a
whimper to trying to do everything themselves has been tried. Most of
us do what we can (the little stuff) and bargain for a decent price
with the mechanic. If you find a good one, stick with him. Avionics and
gyros need frequent repair, it seems. GPS updates and IFR charts are a
hassle to keep current. Good luck!