If you can have the owner take you out for an afternoon before buying it would be a good thing. See if they have any difficulties, or if they baby it in anyway to try and hide something that may be going wrong. Also if anything seems odd, or if you have questions after viewing ask specific questions here. So many people have bought a boat with a strong motor and a fresh jet to turn around and drop another 5 - 8 thousand dollars to make it to the water. Also pay attention to how they launch the boat and checks they my just after and throughout the day. I know I have a fresh motor and jet but I still continuely check the oil for water content, level and the condition of it. Just cause its pretty doesn't mean its correct. Ask anyone I got the ugliest boat around, but its strong enough to pull many back and keep up with the others on runs.
Jason