To find a well maintained plane, get in contact with the maintenance shop of your choice. Usually they have a couple of owners willing to part from their plane, but unwilling to dig though the mud of weird replies on advertising their machine. In most cases they will just pass you to the old guy at the corner without charging for the contact - mostly because by this they keep the plane on their maintenance ...
Don't look for the asking price on most internet portals, they are with no contact to reality. Look at the interesting plans and then decide what they are worth. I rarely hear planes changing owner on asking price ;-).
If you want to go for a ready SID'ed 172, look at the hungarian and czech ads. They have some pretty good mechanics over there and currently they buy cheap, do the SID on their low hourly rates and sell ok. There are some 172 in the 35 region advertised right now. A 172 does have the advantage of being the most common. Cups, Maule, Citabria are quite nice planes, but not as common and especially the Cup is darn slow.