I enjoy buying, fixing up, and selling boats. I usually do it with a 10-12 year old boat. Here are a few things I have learned that may help you with your purchase:1) NADA value on these older boats is usually not accurate. Good shape boats will be worth more money.2) You need to determine the true condition of an older boat and you need to ask alot of questions. Especially if your decision process uses the internet. Those questions may include:-Do you have any sun faded spots on the boat? (a wet sand and buff is around $350)-do you have any scratches on the boat? (one deep scratch in metal flake can be costly)-Do all the pumps work?-Do the brakes work on the trailer? Rotors and calipers are $300, master cylinder is $200-Do the seats have any tears or seam separations? (500 is a good allowance to recover. Sometimes more)-what shape is the carpet in? When was it last replaced? (carpet on 20ft boat is around $1100)-Does it have a cover? What brand?-What shape are the tires in? Are they trailer tires? Do they have uneven wear? (100 per tire on low side)-Does it have hydraulic steering? If not, how hard is it to turn steering wheel? (About 250 to swap out steering cable each)-Are the throttle cables easy to shift and operate? (40 each plus labor)-Is the rubrail in good condition? (350 plus 4 hours labor)-Pay for an engine diagnostic. It is about $100.-What shape are batteries in? After complete charge, a good battery should be around 12.8 volts.-Inquire about shape of electronics, trolling motor-Do all the gauges work? Speedometer does not matter-For cats, bonus if dash has been converted and seats have been converted-Does boat have a keel guard? (125 to 450 for hamby)-What shape are bunks and carpet in?-Do all lids open and close smoothly?-Do all courtesy lights in boxes and around boat work?-Are there any visible exposed wires?-If boat stored in water for extended periods, check bottom for water blisters. Very expensive to fix.-Ask the owner if they are aware of any other issues that will need to be fixed. If you ask the direct question, alot of sellers will be honest with you.I am sure you guys have more tips. Reply to the post and add them. An informed buyer is likely to turn into a happy owner.