An uneven action is corrected through regulation. A complete regulation is where the technician levels the keys, adjusts springs, evens out the hammer blow and distance (the point of where the jack pushes the hammer towards the strings and then lets off to fly freely until impact) changes felts in the bushings and reshapes the hammers. Voices them if necessary.
This job usually runs between 500-1000. Somewhere in between. New strings can run roughly 2K. If they are corroded and very old, it will diminish the sound.
I wouldn't worry myself about the finish too much. Finish doesn't perform.
Hope this helps. Its a start. Only a good technician that actually inspects the piano can give you better info.
I've seen C5 Yamahas , 1990's for roughly 15K in mint condition, if that helps.
Hope this helps at all.