The MOST important thing for someone looking at aircraft ownership, with no previous background, is "What is the typical mission we'd use the airplane for?" This is important so the potential buyer doesn't get too much or to little airplane. Mission includes length of trip (city pairs), average passengers & bags, length of runways, location of flying (ie do we need known ice), requirements to overfly large amounts of terrain and/or water, etc.
In addition to our CJ2+, we also operate a 2007 Cirrus SR22GTS that is owned by our company president. The SR22 is a very efficient traveling machine that could easily turn a 6 hour drive into a 1.5-2hr flight, and I'll try to inform you of costs associated with it.
With any airplane, you want to budget your per-hour direct operating costs to cover 1. fuel, 2. parts, 3. labor, and 4. engine reserve for overhaul. On top of that you add your fixed costs like 1. hangar, 2. insurance, 3. database updates & other subscriptions, etc.
Depending on how high you fly and how hard you push the engine, fuel burns can vary from 12gph to 20gph in the SR22. I like to fly high (10-12k) and at those altitudes 170kt and 13.1gph is fairly common. With 81gal usable in the G1 or G2-era SR22, you can see about 5 hours of endurance with a 45-60min reserve on the back end.
Annuals on our airplane run in the $2-3k ballpark, but they have the potential to go higher. There's lots of "little" stuff Cirrus recommends for this airframe that isn't required and can add expense. I don't remember what TCM says for the IO-550, but $30k for overhaul is a safe bet for budgetary purposes.
Insurance is the Achilles heel of the SR22, because so many people do dumb things flying them. We pay mid-$6k per year for about $400k hull and $1M event/$100k per person liability...but then again we've got 6 named pilots (4 ATPs, 1 with IFR and 1 non-IFR PPL). Its almost impossible to secure insurance on a SR22 without an instrument rating, at ANY price.
Depending on location, expect a hangar to run $200-400/mo for a Cirrus, possibly more.
Also consider the cost of the XM subscription ($50/mo, IIRC), Jepp Charts ($1200/yr, I think) and Garmin databases ($1200-2000, somewhere in that ballpark).
2005-2007 SR22s typically have ask prices in the $250-315k range right now. Of course, for that kind of money one could easily get a Cessna 182/210, Piper Dakota or Saratoga, F33A or A36 Bonanza, Mooney M20K, etc. (if any of those meet the mission requirements) and still have money left over for paint/interior/avionics upgrades and cover hangar/insurance/fuel for a couple years.
If he were interested in something of the Cessna 172 or Archer variety, he could probably have a very nice airplane, easy to insure and ready to fly for well under $100k.