I agree with the rent idea! I've been down this road myself - owned a 172 IFR and all that and put it in a leaseback. Seemed every weekend the wx was lousy so nobody flew and then students would use it during the week and something would break just in time for the weekend when someone had it booked for a long x-country. Long and short - if you don't need the plane for business - rent one and let someone else have the headache.
Also there is a liability issue - I strongly recommend forming an LLC to offset that and the tax issues; so there is more damn expense.
If this plane was a real deal - like $10k less than anything else out there I would say it's worth a shot, but at $28k?
Sounds like they're trying to rake back the money they spent on the motor and prop. The plane itself isn't worth much. I sold a 150 for a friend a little while ago. Got $15k for it - nothing wrong with the plane but it was old and had tons of hours on it. The guy uses it to commute, and he paid cash for it, costs him less to insure than his car!! (go figure!)
If you're still set on it - make the deal by saying you want a fresh annual done by an outside mechanic - anything wrong - seller pays to put it right (parts + labor) - you pay for standard annual + consumables oil, filters etc. That way you get a prebuy plus annual.
Just my 2c's worth......
BP244