Have someone give the engine and outdrive a good look. There are a couple of guys here on the board that I am sure could do that for you. If you can have someone take a look for dry rot. Make sure all the systems work, electric, bilge pumps, lights, batteries. Check out the trailer for rust, good tires, spare, bearings, rollers. Check any canvas for tears or mildew. Look at the seats and flooring for wear. If the electronics are dated or not what you need factor in the cost of replacing them with what you need. Make sure you agree on what goes with the boat such as anchors, safety gear, pfds, skis, etc...
Also make sure you budget to get the boat set up the way you want, downriggers, electronics, nets, gaf, cup holders, am/fm radio/cd player, or any other toys you want to make the boat a joy, not a pain.
Good luck and have fun!